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RESEARCH ARTICLE

Preventive behaviors adults report using to

avoid catching or spreading influenza, United

States, 2015-16 influenza season

Anup Srivastav 1,2*, Tammy A. Santibanez2☯, Peng-Jun Lu2☯, M. Christopher Stringer3‡,

Jill A. Dever 4‡

, Michael Bostwick 5‡

, Marshica Stanley Kurtz 5‡

, Noreen L. Qualls 6‡

, Walter

W. Williams 2‡

1 Leidos Inc, Atlanta, Georgia, United States of America, 2 Immunization Services Division, National Center

for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia,

United States of America, 3 Demographic Statistical Methods Division, U.S. Census Bureau, Durham, North

Carolina, United States of America, 4 Division for Statistical and Data Sciences, RTI International,

Washington, D.C., United States of America, 5 Statistics and Operation Research, RTI International,

Research Triangle Park, North Carolina, United States of America, 6 Division of Global Migration and

Quarantine, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and

Prevention, Atlanta, Georgia, United States of America

☯ These authors contributed equally to this work. ‡ These authors also contributed equally to this work.

* [email protected]

Abstract

Introduction

Influenza vaccination can prevent influenza and potentially serious influenza-related compli-

cations. Although the single best way to prevent influenza is annual vaccination, everyday

preventive actions, including good hygiene, health, dietary, and social habits, might help,

too. Several preventive measures are recommended, including: avoiding close contact with

people who are sick; staying home when sick; covering your mouth and nose when cough-

ing or sneezing; washing your hands often; avoiding touching your eyes, nose, and mouth;

and practicing other good health habits like cleaning and disinfecting frequently touched sur-

faces, getting plenty of sleep, and drinking plenty of fluids. Understanding public acceptance

and current usage of these preventive behaviors can be useful for planning both seasonal

and pandemic influenza prevention campaigns. This study estimated the percentage of

adults in the United States who reported practicing preventive behaviors to avoid catching

or spreading influenza, and explored associations of reported behaviors with sociodemo-

graphic factors.

Methods

We analyzed data from 2015 National Internet Flu Survey, a nationally representative prob-

ability-based Internet panel survey of the non-institutionalized U.S. population �18 years.

The self-reported behaviors used to avoid catching or spreading influenza were grouped

into four and three non-mutually exclusive subgroups, respectively. Weighted proportions

were calculated. Multivariable logistic regression models were used to calculate adjusted

PLOS ONE | https://doi.org/10.1371/journal.pone.0195085 March 30, 2018 1 / 16

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OPEN ACCESS

Citation: Srivastav A, Santibanez TA, Lu P-J,

Stringer MC, Dever JA, Bostwick M, et al. (2018)

Preventive behaviors adults report using to avoid

catching or spreading influenza, United States,

2015-16 influenza season. PLoS ONE 13(3):

e0195085. https://doi.org/10.1371/journal.

pone.0195085

Editor: Vineet Gupta, University of California San

Diego, UNITED STATES

Received: June 5, 2017

Accepted: March 16, 2018

Published: March 30, 2018

Copyright: This is an open access article, free of all

copyright, and may be freely reproduced,

distributed, transmitted, modified, built upon, or

otherwise used by anyone for any lawful purpose.

The work is made available under the Creative

Commons CC0 public domain dedication.

Data Availability Statement: Data used for this

analysis contain potentially identifying information

with restrictions on sharing covered under General

Services Administration (GSA) Directive CIO P

2180.1 (GSA Rules of Behavior for Handling

Personally Identifiable Information [PII]; https://

www.gsa.gov/directives-library/gsa-rules-of-

behavior-for-handling-personally-identifiable-

information-pii-21801-cio-p) or https://www.gsa.

gov/reference/gsa-privacy-program/rules-and-

policies-protecting-pii-privacy-act). A dataset

prevalence differences and to determine independent associations between sociodemo-

graphic characteristics and preventive behavior subgroups.

Results

Common preventive behaviors reported were: 83.2% wash hands often, 80.0% cover

coughs and sneezes, 78.2% stay home if sick with a respiratory illness, 64.4% avoid people

sick with a respiratory illness, 51.7% use hand sanitizers, 50.2% get treatment as soon as

possible, and 49.8% report getting the influenza vaccination. Race/ethnicity, gender, age,

education, income, region, receipt of influenza vaccination, and household size were associ-

ated with use of preventive behaviors after controlling for other factors.

Conclusion

Many adults in the United States reported using preventive behaviors to avoid catching or

spreading influenza. Though vaccination is the most important tool available to prevent influ-

enza, the addition of preventive behaviors might play an effective role in reducing or slowing

transmission of influenza and complement prevention efforts.

Introduction

Influenza vaccination is the best way to prevent influenza and potentially serious influenza-

related complications [1,2]. The Centers for Disease Control and Prevention (CDC) recom-

mends that all persons �6 months of age get an influenza vaccination each influenza season

[3]. Despite the recommendations, adult influenza vaccination coverage remains suboptimal

[4–6] and below Healthy People 2020 targets [7]. Although the single best way to prevent influ- enza is to get vaccinated each year, supplementing it with everyday preventive actions, includ-

ing good hygiene, health, dietary, and social habits, might help, too. CDC and others

recommend several such measures, including: avoiding close contact with people who are sick;

staying home when sick; covering your mouth and nose when coughing or sneezing; washing

your hands often; avoiding touching your eyes, nose, and mouth; and practicing other good

health habits like cleaning and disinfecting frequently touched surfaces, getting plenty of sleep,

and drinking plenty of fluids [8–13].

Previous studies reported that hand hygiene and facemasks prevented household transmis-

sion of influenza virus [14], reduced absenteeism in school children caused by influenza-like

illness (ILI) or laboratory-confirmed influenza [15], and significantly reduced influenza A

(H1N1) viral counts on hands [16]. Other studies [13–19] have assessed various preventive

behaviors that adults adopt other than influenza vaccination (such as social distancing, use of

disinfectants, dietary supplements, maintaining a healthy lifestyle and a healthy diet, getting

treatment as soon as possible) to either avoid catching or spreading the influenza virus. Under-

standing public acceptance and current usage of these preventive behaviors can be useful for

planning both seasonal and pandemic influenza prevention campaigns.

This study uses data from the 2015 National Internet Flu Survey (NIFS) to estimate the per-

centage of adults in the United States who say they practiced preventive behaviors, and to

explore associations of reported behaviors with sociodemographic factors. The results could be

used to prepare targeted and more effective policies and risk communications for the general

public to help prevent catching or spreading influenza, supplementing preexisting vaccination

Preventive behaviors used to avoid catching or spreading influenza to others in United States

PLOS ONE | https://doi.org/10.1371/journal.pone.0195085 March 30, 2018 2 / 16

without PII cannot be posted at this time, but a

limited dataset can be made available upon

request. Data requests from researchers who meet

criteria for access to confidential data may be sent

to Dr. Walter W. Williams ([email protected]);

Technical Monitor, Task Order Contract and

Dontanette L. Cohill ([email protected]); Contracting

Officer Representative, Task Order Contract.

Funding: Leidos Inc. is a U.S. government

contractor agency, not a funder of the project.

Leidos Inc. contributed no funds to the product

only providing support in the form of salary for the

lead author [AS]. Leidos Inc. did not have any role

in the study design, data collection and analysis,

decision to publish, or preparation of the

manuscript. The specific roles of this author are

articulated in the ‘author contributions’ section.

Competing interests: I have read the journal’s

policy and the authors of this manuscript have the

following competing interests: The corresponding

author (AS) is affiliated with Leidos Inc. and this

commercial affiliation does not alter our adherence

to PLOS ONE policies on sharing data and

materials.

policies and outreach strategies. The information also can be used for modelling the spread of

influenza, especially during seasons when the vaccine is not a good match to circulating influ-

enza viruses and everyday preventive actions might be promoted more heavily.

Materials and methods

Survey description

The NIFS is a nationally representative probability-based Internet panel survey of the non-

institutionalized U.S. population �18 years, sponsored by CDC. The 2015 NIFS was con-

ducted by RTI International and GfK Custom Research, LLC. The primary goal of NIFS is to

rapidly collect influenza vaccination-related data early in the influenza season [20]. The NIFS

sample was drawn from GfK’s KnowledgePanel 1

[21], an online panel consisting of a repre-

sentative random sample of the U.S. population. The KnowledgePanel 1

recruitment response

rate was approximately 13% using the American Association for Public Opinion Research

response rate 3 formula [22]. The survey was conducted in English only. For the GfK panel,

participants were initially chosen by a random selection of residential addresses and were con-

tinuously recruited. Persons in selected households were then invited to become a member of

the survey panel. For those who agreed to participate but did not already have Internet access,

GfK provided both a computer and Internet access at no cost. Panelists received unique login

information for accessing surveys online, and were sent e-mails inviting them to participate in

a variety of surveys.

The 2015 NIFS sampling design was a single-stage stratified sample with oversampling of

select subgroups of particular analytical interest. Twelve mutually exclusive design strata were

defined as the interaction of two categorical variables—age (18–49 years, 50–64 years, and 65 years and older) and race/ethnicity (Hispanic, non-Hispanic white, non-Hispanic black, and non-Hispanic other/multiple races)—known for all members of the probability-based Internet

panel. Independent random samples were selected within each design stratum. A total of 6,148

panel members across the 12 design strata were randomly sampled using probabilities of selec-

tion inversely proportional to the KnowledgePanel 1

survey weight (a base weight adjusted for

nonresponse) from 42,075 eligible panelists, with a target of 4,025 completed surveys. A total

of 3,301 completed the survey, with a completion rate of 53.7% (unweighted). Sample mem-

bers were offered the standard KnowledgePanel 1

incentive—1,000 points (equivalent to $1);

they were not offered additional incentives for NIFS participation specifically. The NIFS was

conducted from October 29 to November 11, 2015.

The NIFS collects information about early-season influenza vaccination and knowledge,

attitudes, and behaviors related to influenza and influenza vaccination in the U.S. adult popu-

lation. Additionally, other information such as demographic and access-to-care characteristics

was collected. In the 2015 NIFS, new questions regarding precautions taken to avoid catching

influenza or spreading influenza to others were added to the survey.

Preventive behavior assessment

Information on the preventive behaviors among adults aged �18 years were based on two sur-

vey questions. To determine precautions taken to avoid catching influenza, respondents were

asked: In general, what precautions do you take to avoid catching the flu? Check all that apply. The response options were: getting a flu vaccination; washing your hands often; using hand

sanitizers; avoiding people who are sick with a respiratory illness; covering your mouth and

nose with a mask; taking vitamins; taking herbal medicine or products; other (specify); or

none of the above. To determine precautions taken to avoid spreading influenza to others,

respondents were asked: In general, if you get the flu, what precautions do you take to avoid

Preventive behaviors used to avoid catching or spreading influenza to others in United States

PLOS ONE | https://doi.org/10.1371/journal.pone.0195085 March 30, 2018 3 / 16

passing the flu to others? Check all that apply. The response options were: washing your hands often; using hand sanitizers; staying home if sick with a respiratory illness; covering your

mouth and nose with a mask; covering coughs and sneezes; getting treatment as soon as possi-

ble; other (specify); or none of the above. The verbatim responses were evaluated and back-

coded into existing categories or newly created categories, resulting in 14 behaviors to avoid

catching influenza and 12 behaviors to avoid spreading influenza to others included in this

analysis.

For succinctness, the resulting 14 behaviors to avoid catching influenza were grouped into

four non-mutually exclusive groups (a person could be in multiple groups). These groups

were: 1) getting an influenza vaccination; 2) personal hygiene behaviors (included washing

hands often, using hand sanitizers, and using disinfectants); 3) personal health and dietary

behaviors (included maintaining a healthy diet, getting regular exercise, getting adequate rest,

maintaining a healthy lifestyle, taking vitamins, taking herbal medicine or products, and

drinking ample fluids); and/or 4) interpersonal social behaviors (included avoiding people

who are sick with a respiratory illness, covering mouth and nose with a mask, and avoiding

others in general). Likewise, the 12 behaviors to avoid spreading influenza to others were

grouped into three non-mutually exclusive groups. These groups were: 1) personal hygiene

behaviors (included washing hands often and using hand sanitizers); 2) personal health and

dietary behaviors (included getting adequate rest, getting treatment as soon as possible, drink-

ing ample fluids, and taking supplements); and/or 3) interpersonal social behaviors (included

staying home if sick with a respiratory illness, covering your mouth and nose with a mask, cov-

ering coughs and sneezes, avoiding others in general, and using disinfectants). A person could

be included in more than one of these groupings.

Influenza vaccination and other variables

Other sociodemographic variables collected during the NIFS or as part of GfK panel recruit-

ment included age, gender, race/ethnicity, marital status, educational level, employment status,

annual household income, region of residence, metropolitan statistical area (MSA) status, and

household size. Receipt of influenza vaccination (as of the date respondents completed the

online survey) also is reported based upon the survey question, A flu vaccination can be a shot injected in the arm or a mist sprayed in the nose by a doctor, nurse, pharmacist or other health professional. Since July 1, 2015, have you had a flu vaccination? Influenza vaccination coverage estimates represent the cumulative proportion of persons vaccinated by the time when the sur-

vey was completed [20].

Data analysis

Unadjusted proportions are reported along with 95% confidence intervals. All analyses were

weighted to the U.S. population of non-institutionalized adults using the 2015 March Supple-

ment of the Current Population Survey estimates after adjusting the NIFS base weights for

nonresponse. A bias analysis was conducted to determine the influence of nonresponse in the

results using demographic and geographic information available in the KnowledgePanel 1

sampling frame. Tests were performed with a significance level set at α = 0.05. Multivariable logistic regression was conducted to calculate adjusted prevalence differences (adjusting for all

variables included in the model) and to determine the independent associations between

sociodemographic characteristics and preventive behavior subgroups. Separate regression

models were run for each preventive behavior subgroup because the groupings were not mutu-

ally exclusive. T-tests were used to test differences in adjusted coverage within each covariate

category compared with appropriate reference groups for each preventive behavior subgroup.

Preventive behaviors used to avoid catching or spreading influenza to others in United States

PLOS ONE | https://doi.org/10.1371/journal.pone.0195085 March 30, 2018 4 / 16

All analyses were performed using SAS, release 9.4 (SAS Inc. Cary, NC, USA) and SUDAAN,

release 11.0.1 (Research Triangle Institute, Research Triangle Park, NC, USA).

The NIFS was designated as “Public Health Non-Research” during the determination for

applicability of human subjects’ regulations, because the activity is not intended to include

applicable research, but to access the implementation, coverage, performance, and/or satisfac-

tion with an existing public health program, service, function, intervention or recommenda-

tion. Data security was addressed and informed consent was sought.

Results

The sociodemographic characteristics of the study population are presented in Table 1. The

majority of respondents were aged 18–49 years (54.7%), female (51.7%), of non-Hispanic

white race ethnicity (65.5%), were married or living with a partner (57.9%), had high school or

higher education (88.0%), were employed (58.5%), lived in a metropolitan statistical area

(83.5%), and lived in households of at least two or more (88.8%) (Table 1).

Among adults aged �18 years, 39.9% reported having received influenza vaccination by

early November (Table 1). The percentages of adults reporting each preventative behavior to

avoid catching influenza and spreading influenza to others are presented in Fig 1. The most

commonly reported behaviors for avoiding catching influenza were: washing hands often

(83.2%), avoiding people who are sick with a respiratory illness (64.4%), using hand sanitizers

(51.6%), getting an influenza vaccination (49.8%), taking vitamins (44.1%), covering mouth

and nose with a mask (19.1%), and taking herbal medicine or products (11.8%) (Fig 1). The

most commonly reported behaviors for avoiding spreading influenza to others were: covering

coughs and sneezes (80.0%), washing hands often (79.2%), staying home if sick with a respira-

tory illness (78.2%), using hand sanitizers (51.7%), getting treatment as soon as possible

(50.2%), and covering mouth and nose with a mask (27.3%) (Fig 1).

Getting an influenza vaccination was not the most common preventive behavior reported

by respondents. The most common preventive behaviors and approaches reported were per-

sonal hygiene behaviors (84.9%), followed by interpersonal social behaviors (68.0%), influenza

vaccination (49.8%), and personal health and dietary behaviors (47.1%) (Table 2). The most

common behaviors to avoid spreading influenza reported were interpersonal social behaviors

(89.5%), followed by personal hygiene behaviors (81.1%) and personal health and dietary

behaviors (50.5%). In the bivariate analyses, characteristics associated with more frequent

adoption of behaviors to avoid catching or spreading influenza included, age �50 years, being

female, non-Hispanic white or non-Hispanic other or multiple races, being married/living

with partner or widowed/divorced/separated, having some college or bachelor’s degree or

higher education, having annual household income �$35,000, and having received influenza

vaccination (Table 2).

Only a few of the variables found to be significantly associated with the behaviors based on

the bivariate analyses remained significant in the multivariable models presented in Table 3.

Characteristics independently associated with a respondent reporting that getting an influenza

vaccination is a behavior they use to avoid catching influenza were: age �50 years, being

female, having annual household income �$75,000, not being in the workforce, and self-

report that they had received an influenza vaccination by the time of the interview for the

2015–16 influenza season. Characteristics independently associated with use of any of the per-

sonal hygiene behaviors were: age �50 years, being female, some college and bachelor’s degree

or higher education, having annual household income $50,000-$74,999, and having �3 per-

sons in the household. Characteristics independently associated with use of any of the personal

health and dietary behaviors were: age �65 years, being female, some college, and having

Preventive behaviors used to avoid catching or spreading influenza to others in United States

PLOS ONE | https://doi.org/10.1371/journal.pone.0195085 March 30, 2018 5 / 16

Table 1. Sociodemographic characteristics among adults aged �18 years–United States, National Internet Flu

Survey 2015.

Characteristic Unweighted Sample Size, No. Weighted Percentage % (95% CI)

Total 3,301 100.0

Age

18–49 years 1,508 54.7 (53.8, 55.6)

50–64 years 1,033 26.0 (25.3, 26.7)

�65 years 760 19.3 (18.6, 19.9)

Gender

Male 1,622 48.3 (46.3, 50.4)

Female 1,679 51.7 (49.6, 53.7)

Race/ethnicity

Non-Hispanic white only 1,922 65.5 (64.3, 66.7)

Non-Hispanic black only 494 11.8 (11.0, 12.6)

Hispanic 460 14.1 (13.0, 15.3)

Non-Hispanic, other or multiple races 425 8.6 (7.7, 9.5)

Marital status

Married/living with partner 1,950 57.9 (55.9, 59.9)

Widowed/divorced/separated 616 17.7 (16.2, 19.2)

Never married 735 24.5 (22.7, 26.3)

Education level

Less than high school 269 12.0 (10.5, 13.6)

High school 892 29.4 (27.6, 31.3)

Some college 956 28.5 (26.8, 30.4)

Bachelor’s degree or higher 1,184 30.1 (28.4, 31.8)

Employment

Employed 1,862 58.5 (56.6, 60.3)

Unemployed 188 6.3 (5.3, 7.5)

Not in work force 1,251 35.2 (33.5, 36.9)

Annual household income

<$35,000 945 27.2 (25.5, 29.1)

$35,000-$49,999 374 11.6 (10.3, 13.0)

$50,000-$74,999 628 17.9 (16.4, 19.5)

�$75,000 1,354 43.3 (41.3, 45.3)

Region of residence

Northeast 590 18.1 (16.6, 19.7)

Midwest 693 21.4 (19.8, 23.1)

South 1,185 37.1 (35.1, 39.0)

West 833 23.4 (21.8, 25.1)

MSA status

Metro 2,885 85.0 (83.5, 86.4)

Non-metro 416 15.0 (13.6, 16.5)

Household size

One 723 21.2 (19.6, 22.9)

Two 1,272 36.1 (34.3, 37.9)

Three or more 1,306 42.7 (40.8, 44.7)

Received influenza vaccination

Yes 1,354 39.9 (38.0, 41.8)

No 1,894 60.1 (58.2, 62.0)

https://doi.org/10.1371/journal.pone.0195085.t001

Preventive behaviors used to avoid catching or spreading influenza to others in United States

PLOS ONE | https://doi.org/10.1371/journal.pone.0195085 March 30, 2018 6 / 16

received an influenza vaccination. Characteristics independently associated with use of any of

the interpersonal social behaviors were: age �65 years, being female, some college, having

annual household income $35,000-$49,999, and residence in the south (Table 3).

The characteristics independently associated with a respondent reporting using any of the

personal hygiene behaviors to avoid spreading influenza to others were: age �50 years, being

female, some college or bachelor’s degree or higher education, having received an influenza

vaccination, and having �3 persons in the household. Characteristics independently associ-

ated with use of any of the personal health and dietary behaviors were: age �65 years, being

female, being of non-Hispanic black race/ethnicity, having income �$75,000, living in the

northeast, having received an influenza vaccination, and having �2 persons in the household.

Characteristics independently associated with use of any of the interpersonal social behaviors

Fig 1. Preventive behaviors used by adults as precautions taken to avoid catching influenza or spreading influenza.

https://doi.org/10.1371/journal.pone.0195085.g001

Preventive behaviors used to avoid catching or spreading influenza to others in United States

PLOS ONE | https://doi.org/10.1371/journal.pone.0195085 March 30, 2018 7 / 16

Table 2. Unadjusted preventive behaviors used by adults to avoid catching or spreading influenza by sociodemographic characteristics.

Behaviors Adopted to Avoid Catching Influenza Behaviors Adopted to Avoid Spreading Influenza

Getting an

Influenza

Vaccination

Personal

Hygiene

Behaviors a

Personal Health

and Dietary

Behaviors b

Interpersonal

Social Behaviors c

Personal

Hygiene

Behaviors a

Personal Health

and Dietary

Behaviors b

Interpersonal

Social Behaviors c

Characteristic % (95% CI) % (95% CI) % (95% CI) % (95% CI) % (95% CI) % (95% CI) % (95% CI)

Overall 49.8 (47.8, 51.8) 84.9 (83.3, 86.4) 47.1 (45.1, 49.1) 68.0 (66.0, 69.9) 81.1 (79.3, 82.7) 50.5 (48.5, 52.5) 89.5 (88.0, 90.8)

Age

18–49 years d

40.4 (37.5, 43.4) 82.4 (79.7, 84.7) 44.9 (42.0, 47.9) 65.0 (62.0, 67.9) 79.7 (76.9, 82.1) 46.6 (43.6, 49.6) 86.6 (84.3, 88.6)

50–64 years 53.5� (50.0, 56.9) 87.1� (84.4,

89.4)

47.4 (44.0, 50.8) 69.2 (65.8, 72.3) 82.6 (79.8, 85.2) 50.7 (47.2, 54.1) 90.7� (88.1, 92.7)

�65 years 71.5� (67.7, 75.0) 89.1� (86.6,

91.2)

52.8� (48.8, 56.8) 74.7� (71.0, 78.1) 83.0 (79.9, 85.6) 61.6� (57.6, 65.4) 96.0� (94.1, 97.2)

Gender

Male d

46.4 (43.6, 49.2) 79.3 (76.6, 81.7) 41.5 (38.7, 44.3) 64.6 (61.8, 67.4) 74.7 (72.0, 77.3) 46.4 (43.6, 49.3) 85.7 (83.3, 87.8)

Female 53.0� (50.2, 55.8) 90.2� (88.1,

91.9)

52.3� (49.5, 55.2) 71.1� (68.4, 73.6) 87.0� (84.8,

88.9)

54.3� (51.5, 57.2) 93.0� (91.3, 94.4)

Race/ethnicity

Non-Hispanic

white only d

52.8 (50.4, 55.2) 86.2 (84.3, 87.9) 47.1 (44.6, 49.5) 69.6 (67.2, 71.8) 82.2 (80.1, 84.0) 49.7 (47.2, 52.1) 91.1 (89.4, 92.5)

Non-Hispanic

black only

41.5� (36.3, 46.8) 83.5 (78.6, 87.4) 46.3 (40.9, 51.8) 63.5� (57.9, 68.8) 79.1 (73.8, 83.6) 56.9� (51.3, 62.3) 86.7� (82.1, 90.2)

Hispanic 45.1� (39.1, 51.2) 82.2 (76.3, 86.8) 46.4 (40.4, 52.6) 62.8� (56.5, 68.8) 80.6 (74.7, 85.4) 50.9 (44.8, 57.0) 86.0� (80.8, 89.9)

Non-Hispanic,

other or multiple

races

46.2 (39.7, 52.9) 81.5 (74.3, 87.0) 49.3 (42.6, 55.9) 70.2 (63.5, 76.2) 76.3 (69.1, 82.2) 47.5 (40.9, 54.2) 86.7 (80.7, 91.1)

Marital status

Married/living with

partner d

53.4 (50.8, 55.9) 87.7 (85.7, 89.4) 49.7 (47.1, 52.3) 70.3 (67.9, 72.7) 84.0 (81.9, 85.9) 53.0 (50.4, 55.5) 91.5 (89.8, 93.0)

Widowed/divorced/

separated

54.4 (49.6, 59.0) 87.2 (83.5, 90.2) 47.2 (42.5, 51.9) 69.9 (65.2, 74.3) 80.3 (75.9, 84.0) 55.7 (50.9, 60.3) 91.5 (88.3, 93.9)

Never married 38.1� (33.9, 42.4) 76.7� (72.6,

80.4)

40.9� (36.7, 45.2) 60.9� (56.5, 65.2) 74.7� (70.6,

78.5)

41.0� (36.8, 45.4) 83.1� (79.4, 86.4)

Education level

Less than high

school d

43.5 (36.6, 50.6) 73.4 (66.2, 79.5) 41.9 (35.0, 49.1) 61.3 (54.0, 68.2) 71.8 (64.7, 77.9) 49.8 (42.7, 57.0) 81.5 (75.2, 86.5)

High school 47.4 (43.6, 51.1) 80.5 (77.1, 83.5) 44.3 (40.6, 48.1) 65.7 (61.9, 69.3) 77.8 (74.3, 80.9) 48.7 (45.0, 52.5) 87.2 (84.3, 89.7)

Some college 46.1 (42.4, 49.8) 89.8� (87.2,

92.0)

50.4� (46.6, 54.2) 70.9� (67.4, 74.3) 85.6� (82.6,

88.1)

54.9 (51.1, 58.6) 91.1� (88.4, 93.1)

Bachelor’s degree

or higher

58.2� (55.0, 61.5) 89.2� (86.9,

91.1)

48.7 (45.5, 52.0) 70.0� (66.9, 73.0) 83.7� (80.9,

86.2)

48.4 (45.1, 51.6) 93.3� (91.3, 94.9)

Employment

Employed d

45.2 (42.6, 47.8) 85.8 (83.6, 87.7) 46.4 (43.7, 49.0) 66.2 (63.6, 68.7) 82.1 (79.8, 84.2) 47.2 (44.6, 49.9) 88.9 (87.0, 90.6)

Unemployed 39.1 (30.8, 48.1) 78.4 (69.6, 85.2) 35.6� (27.8, 44.2) 61.1 (51.8, 69.7) 76.1 (67.0, 83.4) 46.4 (37.6, 55.4) 84.0 (75.8, 89.8)

Not in work force 59.4� (56.2, 62.6) 84.7 (81.9, 87.1) 50.4 (47.1, 53.6) 72.1� (68.9, 75.1) 80.3 (77.4, 82.9) 56.7� (53.4, 60.0) 91.4 (89.1, 93.2)

Annual household

income

<$35,000 d

42.0 (38.2, 45.9) 77.9 (74.2, 81.1) 42.5 (38.7, 46.4) 62.7 (58.7, 66.6) 75.0 (71.3, 78.4) 47.5 (43.6, 51.4) 81.7 (78.1, 84.8)

$35,000-$49,999 46.3 (40.4, 52.3) 85.0� (79.5,

89.3)

47.9 (41.9, 54.0) 71.6� (65.8, 76.7) 82.5� (76.9,

87.0)

50.3 (44.3, 56.4) 90.1� (85.8, 93.2)

$50,000-$74,999 50.5� (45.8, 55.1) 88.7� (85.2,

91.5)

50.4� (45.8, 55.1) 66.1 (61.4, 70.5) 83.9� (79.8,

87.3)

48.8 (44.2, 53.5) 93.7� (90.6, 95.8)

�$75,000 55.4� (52.3, 58.4) 87.7� (85.3,

89.8)

48.3� (45.3, 51.4) 71.1� (68.1, 73.8) 83.3� (80.7,

85.6)

53.2� (50.1, 56.2) 92.5� (90.5, 94.1)

(Continued)

Preventive behaviors used to avoid catching or spreading influenza to others in United States

PLOS ONE | https://doi.org/10.1371/journal.pone.0195085 March 30, 2018 8 / 16

were: age �50 years, being female, some college or bachelor’s degree or higher education, hav-

ing income �$35,000, and a larger household size with �2 persons (Table 3).

In the bias analysis to determine the influence of nonresponse in the results, tests for the

smallest race/ethnicity group (non-Hispanic other/multiple category) showed the highest

detectable levels of bias, most falling below substantively meaningful levels of 10 percentage

points.

Discussion

The best way to prevent seasonal influenza is to get vaccinated each year. However, good

health habits like covering coughs and washing hands often can help slow the spread of

Table 2. (Continued )

Behaviors Adopted to Avoid Catching Influenza Behaviors Adopted to Avoid Spreading Influenza

Getting an

Influenza

Vaccination

Personal

Hygiene

Behaviors a

Personal Health

and Dietary

Behaviors b

Interpersonal

Social Behaviors c

Personal

Hygiene

Behaviors a

Personal Health

and Dietary

Behaviors b

Interpersonal

Social Behaviors c

Characteristic % (95% CI) % (95% CI) % (95% CI) % (95% CI) % (95% CI) % (95% CI) % (95% CI)

Region of residence

Northeast d

52.2 (47.5, 56.9) 85.5 (81.9, 88.6) 47.2 (42.5, 51.9) 62.9 (58.2, 67.4) 80.3 (76.1, 83.9) 55.1 (50.3, 59.7) 88.3 (84.7, 91.2)

Midwest 52.3 (48.0, 56.5) 86.1 (82.6, 89.0) 47.5 (43.2, 51.8) 67.3 (63.0, 71.2) 83.4 (79.9, 86.5) 44.5� (40.3, 48.7) 91.8 (88.8, 94.0)

South 50.8 (47.4, 54.1) 83.4 (80.4, 86.1) 46.4 (43.1, 49.8) 71.3� (68.1, 74.4) 81.1 (78.1, 83.8) 55.3 (51.9, 58.7) 88.4 (85.8, 90.6)

West 44.2� (40.2, 48.3) 85.7 (82.1, 88.6) 47.7 (43.6, 51.9) 67.1 (63.0, 71.0) 79.4 (75.5, 82.8) 44.9� (40.8, 49.1) 89.9 (86.8, 92.4)

Received influenza

vaccination

Yes 89.5� (87.2, 91.4) 89.1� (86.8,

91.0)

46.2 (43.1, 49.3) 69.8 (66.8, 72.7) 85.7� (83.2,

87.8)

55.6� (52.5, 58.7) 93.2� (91.4, 94.7)

No d

24.7 (22.6, 27.0) 83.9 (81.7, 86.0) 49.0 (46.3, 51.7) 68.5 (65.9, 71.0) 79.8 (77.4, 82.0) 48.3 (45.6, 51.0) 88.9 (86.9, 90.6)

MSA status

Metro 50.4 (48.3, 52.6) 85.1 (83.4, 86.8) 46.8 (44.7, 49.0) 68.3 (66.2, 70.3) 81.1 (79.2, 82.9) 50.6 (48.4, 52.8) 89.5 (87.9, 90.8)

Non-metro d

46.2 (40.9, 51.7) 83.6 (78.9, 87.5) 48.4 (43.0, 53.9) 66.0 (60.5, 71.1) 80.9 (76.2, 84.9) 50.1 (44.6, 55.5) 89.6 (85.2, 92.8)

Household size

One 47.1 (42.8, 51.4) 77.8� (73.7,

81.5)

45.4 (41.1, 49.8) 62.9� (58.4, 67.2) 72.9� (68.5,

76.8)

43.3� (39.1, 47.6) 85.2� (81.5, 88.2)

Two 56.5� (53.3, 59.6) 86.0 (83.3, 88.3) 47.8 (44.7, 51.0) 70.4 (67.3, 73.3) 81.8 (78.9, 84.3) 53.0 (49.8, 56.1) 90.6 (88.0, 92.6)

Three or more d

45.6 (42.4, 48.8) 87.5 (85.0, 89.6) 47.3 (44.1, 50.5) 68.4 (65.3, 71.4) 84.5 (82.0, 86.8) 52.0 (48.8, 55.3) 90.7 (88.6, 92.4)

CI confidence interval. �Significant at P < 0.05 by t-test compared to the reference group. a To avoid catching influenza, personal hygiene behaviors is comprised of the following behaviors: a) washing your hands often; b) using hand sanitizers; c) using

disinfectants.

To avoid spreading influenza to others, personal hygiene behaviors is comprised of the following behaviors: a) washing your hands often; b) using hand sanitizers. b To avoid catching influenza, personal health and dietary behaviors is comprised of the following behaviors: a) maintaining a healthy diet; b) getting regular exercise; c)

getting adequate rest; d) maintaining a healthy lifestyle; e) taking vitamins; f) taking herbal medicine or products; g) drinking ample fluids.

To avoid spreading influenza to others, personal health and dietary behaviors is comprised of the following behaviors: a) getting adequate rest; b) getting treatment as

soon as possible; c) drinking ample fluids; d) taking supplements. c To avoid catching influenza, interpersonal social behaviors is comprised of the following behaviors: a) avoiding people who are sick with a respiratory illness; b)

covering your mouth and nose with a mask; c) avoiding others in general.

To avoid spreading influenza to others, interpersonal social behaviors is comprised of the following behaviors: a) staying home if sick with a respiratory illness; b)

covering your mouth and nose with a mask; c) covering coughs and sneezes; d) avoiding others in general; e) using disinfectants. d Reference level.

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Preventive behaviors used to avoid catching or spreading influenza to others in United States

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Table 3. Adjusted estimates of preventive behavior responses used by adults to avoid catching or spreading influenza.

Behaviors Adopted to Avoid Catching Influenza Behaviors Adopted to Avoid Spreading Influenza

Getting an

Influenza

Vaccination

Personal

Hygiene

Behaviors a

Personal Health

and Dietary

Behaviors b

Interpersonal

Social Behaviors c

Personal

Hygiene

Behaviors a

Personal Health

and Dietary

Behaviors b

Interpersonal

Social Behaviors c

Characteristic APD d

(95% CI) APD (95% CI) APD (95% CI) APD (95% CI) APD (95% CI) APD (95% CI) APD (95% CI)

Age

18–49 years Referent Referent Referent Referent Referent Referent Referent

50–64 years 6.5� (2.5, 10.5) 6.6� (2.7, 10.5) 2.6 (-2.5, 7.7) 4.0 (-0.9, 8.8) 5.1� (1.0, 9.2) 3.5 (-1.6, 8.5) 4.8� (1.5, 8.1)

�65 years 12.8� (6.6, 18.9) 8.5� (4.0, 13.0) 7.5� (0.5, 14.4) 6.9� (0.3, 13.6) 5.7� (0.5, 11.0) 12.1� (5.3, 18.9) 8.8� (5.3, 12.2)

Gender

Male Referent Referent Referent Referent Referent Referent Referent

Female 3.2� (0.0, 6.3) 9.6� (6.6, 12.6) 10.3� (6.2, 14.3) 4.9� (1.0, 8.8) 11.2� (8.0, 14.4) 5.3� (1.3, 9.3) 5.7� (3.1, 8.3)

Race/ethnicity

Non-Hispanic

white only

Referent Referent Referent Referent Referent Referent Referent

Non-Hispanic

black only

-4.6 (-9.5, 0.4) 2.0 (-2.1, 6.1) 3.8 (-2.5, 10.1) -3.6 (-9.7, 2.5) 0.2 (-4.9, 5.2) 9.6� (3.6, 15.7) 0.1 (-3.2, 3.5)

Hispanic 0.7 (-4.8, 6.3) -0.0 (-4.7, 4.6) 5.2 (-1.7, 12.2) -2.6 (-9.3, 4.1) 2.7 (-2.3, 7.7) 5.3 (-1.5, 12.1) -0.9 (-4.7, 2.8)

Non-Hispanic,

other or multiple

races

-1.3 (-6.4, 3.8) -3.1 (-8.9, 2.7) 4.9 (-2.4, 12.2) 3.5 (-3.1, 10.0) -3.9 (-10.0, 2.3) 1.9 (-5.5, 9.4) -2.9 (-8.0, 2.1)

Marital status

Married/living with

partner

Referent Referent Referent Referent Referent Referent Referent

Widowed/divorced/

separated

1.7 (-3.2, 6.5) 2.4 (-2.4, 7.1) -4.1 (-10.7, 2.4) 2.0 (-4.0, 8.0) -0.2 (-5.6, 5.2) 4.8 (-1.7, 11.3) 1.9 (-1.9, 5.6)

Never married 3.0 (-1.9, 8.0) -2.0 (-6.5, 2.6) -5.4 (-11.8, 0.9) -2.4 (-8.3, 3.5) -1.3 (-6.4, 3.7) -4.6 (-11.0, 1.7) 0.4 (-3.2, 4.1)

Education level

Less than high

school

Referent Referent Referent Referent Referent Referent Referent

High school 0.6 (-5.4, 6.7) 5.8 (-1.5, 13.0) 2.9 (-5.2, 11.1) 3.9 (-4.2, 12.1) 5.2 (-2.0, 12.4) 0.6 (-7.5, 8.8) 2.8 (-2.3, 8.0)

Some college 0.9 (-5.1, 7.0) 14.8� (7.6, 22.0) 9.3� (0.9, 17.6) 9.2� (1.1, 17.3) 12.8� (5.7, 19.9) 7.7 (-0.6, 16.0) 5.8� (0.7, 11.0)

Bachelor’s degree

or higher

5.1 (-1.2, 11.4) 13.7� (6.2, 21.1) 7.8 (-0.9, 16.4) 8.0 (-0.4, 16.3) 11.1� (3.7, 18.5) 0.6 (-8.0, 9.2) 7.3� (1.9, 12.6)

Employment

Employed Referent Referent Referent Referent Referent Referent Referent

Unemployed 3.4 (-4.2, 11.0) -1.2 (-7.3, 4.9) -4.3 (-13.5, 5.0) 1.9 (-7.2, 11.0) 0.5 (-5.9, 7.0) 2.7 (-6.6, 12.0) 1.9 (-2.7, 6.5)

Not in work force 5.1� (1.0, 9.1) -2.8 (-6.9, 1.2) 2.4 (-2.8, 7.6) 4.6 (-0.4, 9.6) -3.2 (-7.5, 1.1) 5.1 (-0.0, 10.2) 0.7 (-2.5, 3.9)

Annual household

income

<$35,000 Referent Referent Referent Referent Referent Referent Referent

$35,000-$49,999 2.5 (-2.5, 7.4) 3.3 (-2.2, 8.8) 4.7 (-2.6, 12.0) 7.0� (0.1, 13.9) 3.5 (-2.5, 9.4) 2.3 (-5.0, 9.7) 6.8� (2.3, 11.4)

$50,000-$74,999 4.5 (-0.3, 9.4) 5.0� (0.6, 9.5) 5.9 (-0.6, 12.5) 1.2 (-5.0, 7.5) 4.6 (-0.4, 9.6) 0.9 (-5.4, 7.2) 9.4� (5.2, 13.5)

�$75,000 9.7� (4.8, 14.6) 2.6 (-2.1, 7.4) 4.0 (-2.2, 10.2) 5.2 (-0.8, 11.1) 2.4 (-2.8, 7.5) 6.5� (0.3, 12.7) 8.4� (4.2, 12.6)

Region of residence

Northeast Referent Referent Referent Referent Referent Referent Referent

Midwest 0.4 (-4.5, 5.2) 0.3 (-4.1, 4.6) -0.4 (-6.7, 6.0) 4.0 (-2.1, 10.2) 2.7 (-2.2, 7.6) -11.6� (-17.9, -5.3) 3.6 (-0.4, 7.5)

South 1.1 (-3.3, 5.5) -1.9 (-5.9, 2.2) -1.5 (-7.2, 4.3) 8.7� (3.1, 14.3) 1.0 (-3.6, 5.5) -2.0 (-7.7, 3.7) 0.9 (-2.8, 4.7)

West -3.9 (-8.6, 0.7) 0.5 (-3.8, 4.8) 0.4 (-5.9, 6.7) 3.9 (-2.2, 10.0) -0.7 (-5.6, 4.3) -10.7� (-17.0, -4.5) 2.2 (-1.8, 6.2)

Received influenza

vaccination

(Continued)

Preventive behaviors used to avoid catching or spreading influenza to others in United States

PLOS ONE | https://doi.org/10.1371/journal.pone.0195085 March 30, 2018 10 / 16

influenza viruses. The findings of this study provide insight into various preventive behaviors

reportedly used by adults in the United States, either to prevent getting infected with influenza

or to prevent transmitting influenza to others when infected with influenza viruses.

The distribution of self-reported preventive behaviors most frequently used by U.S. adults

observed in this study were somewhat similar to the distribution reported previously from a

national survey during the 2009 H1N1 influenza pandemic [17] which explored racial/ethnic

differences in the adoption of preventive behaviors. Similarities observed were in frequency of

use of the following behaviors: getting the seasonal influenza vaccine, washing hands often,

using hand sanitizer, covering coughs and sneezes, avoiding people who are sick with a respi-

ratory illness, and taking herbal supplements. Differences observed were in the following

behaviors: frequency of use of disinfectants and avoiding others in general was lower in this

study than previously reported and frequency of getting treatment as soon as possible was

higher in this study than previously reported.

Use of facemasks and hand washing were reported to prevent household influenza trans-

mission when healthy family members started using these measures within 36 hours of symp-

tom onset with an infected family member [14]; adherence to the interventions, however, was

reported to be low. A study [15] reported hand hygiene behavior (e.g., washing hands twice

each day) reduced ILI or laboratory-confirmed influenza in school children by 40% and 50%,

Table 3. (Continued )

Behaviors Adopted to Avoid Catching Influenza Behaviors Adopted to Avoid Spreading Influenza

Getting an

Influenza

Vaccination

Personal

Hygiene

Behaviors a

Personal Health

and Dietary

Behaviors b

Interpersonal

Social Behaviors c

Personal

Hygiene

Behaviors a

Personal Health

and Dietary

Behaviors b

Interpersonal

Social Behaviors c

Characteristic APD d

(95% CI) APD (95% CI) APD (95% CI) APD (95% CI) APD (95% CI) APD (95% CI) APD (95% CI)

Yes 61.6� (58.4, 64.8) 2.9 (-0.1, 5.8) -5.4� (-9.5, -1.2) -1.1 (-5.1, 2.9) 4.5� (1.3, 7.7) 4.7� (0.5, 8.8) 1.9 (-0.7, 4.5)

No Referent Referent Referent Referent Referent Referent Referent

MSA status

Metro 2.0 (-2.4, 6.4) -0.1 (-4.3, 4.1) -2.7 (-8.8, 3.3) 2.6 (-3.3, 8.4) -0.4 (-4.9, 4.1) -1.8 (-7.7, 4.2) -1.5 (-5.0, 2.0)

Non-metro Referent Referent Referent Referent Referent Referent Referent

Household size

One -3.9 (-9.7, 1.9) -10.4� (-16.4,

-4.3)

1.2 (-5.7, 8.1) -4.5 (-11.4, 2.3) -10.4� (-16.9,

-3.9)

-10.7� (-17.6, -3.9) -4.7� (-9.2, -0.3)

Two 1.5 (-2.3, 5.3) -4.4� (-7.8, -1.0) -1.2 (-6.1, 3.8) -1.4 (-6.0, 3.1) -4.8� (-8.6, -1.0) -3.3 (-8.1, 1.6) -2.6 (-5.6, 0.3)

Three or more Referent Referent Referent Referent Referent Referent Referent

APD Adjusted prevalence difference; CI confidence interval. �Significant at P < 0.05 by t-test compared to the reference group. a To avoid catching influenza, personal hygiene behaviors is comprised of the following behaviors: a) washing your hands often; b) using hand sanitizers; c) using

disinfectants.

To avoid spreading influenza to others, personal hygiene behaviors is comprised of the following behaviors: a) washing your hands often; b) using hand sanitizers. b To avoid catching influenza, personal health and dietary behaviors is comprised of the following behaviors: a) maintaining a healthy diet; b) getting regular exercise; c)

getting adequate rest; d) maintaining a healthy lifestyle; e) taking vitamins; f) taking herbal medicine or products; g) drinking ample fluids.

To avoid spreading influenza to others, personal health and dietary behaviors is comprised of the following behaviors: a) getting adequate rest; b) getting treatment as

soon as possible; c) drinking ample fluids; d) taking supplements. c To avoid catching influenza, interpersonal social behaviors is comprised of the following behaviors: a) avoiding people who are sick with a respiratory illness; b)

covering your mouth and nose with a mask; c) avoiding others in general.

To avoid spreading influenza to others, interpersonal social behaviors is comprised of the following behaviors: a) staying home if sick with a respiratory illness; b)

covering your mouth and nose with a mask; c) covering coughs and sneezes; d) avoiding others in general; e) using disinfectants. d Adjusted prevalence differences, adjusted for all variables included in the table.

https://doi.org/10.1371/journal.pone.0195085.t003

Preventive behaviors used to avoid catching or spreading influenza to others in United States

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respectively. Another study [18] reported a significant association of regular physical exercise,

optimal hand hygiene, face mask use when going to hospitals, and not sharing towels and

handkerchiefs with a lower likelihood of reporting ILI. In addition, in another report [16],

using alcohol-based hand sanitizers significantly reduced H1N1 viral counts on hands. These

studies [14–16,18] provided scientific evidence that facemasks and hand hygiene behaviors are

effective in reducing the transmission of influenza and ILI, suggesting that nonpharmaceutical

interventions play important roles in mitigating pandemic and interpandemic influenza.

The high prevalence of self-reported preventive behavior use observed in this study demon-

strates that the U.S. adult population are aware of and adopting some, if not most of these pre-

ventive behaviors to avoid catching influenza or to avoid spreading influenza to others.

Though research has shown that these simple measures are highly effective in reducing virus

transmission [19,23], some behavioral interventions are generally perceived as intrusive and/

or different from typical day-to-day behavior (such as use of masks and gloves). Consequently,

parents and teachers generally see these interventions as unacceptable in the context of sea-

sonal influenza. Therefore, it has been suggested to target general etiquette practices (such as

covering one’s cough and washing hands), as they are perceived as normal (by parents) and

acceptable (by teachers) [24].

Through the use of multivariable modeling in our study, we found that several characteris-

tics were independently associated with either higher or lower likelihood of adoption of the

preventive behaviors studied. We observed that older adults, with a higher educational level,

and from middle-higher income settings were more likely to adopt all or most of the behaviors

than younger adults, those who were less educated, and those in a low-income setting. Similar

results were reported [25] where older adults with a higher educational level and higher socio-

economic status were more likely to know that washing their hands with soap before and after

touching raw poultry meat and using gloves were hygienic practices to avoid spreading the

avian influenza virus through food. A significant association was also reported between those

who fail to wash hands and use gloves and the lack of knowledge that these are standard

hygienic practices to avoid spreading the avian influenza virus through food [25].

A systematic review [26] reported significantly higher reduction of respiratory infection

among people in low/middle-income setting along with variation in the effectiveness of hand

hygiene intervention. For adults, it has been suggested that a real or perceived financial or

social disincentive might not allow them to stay home when sick with an infectious disease

[24]. This finding might help explain the difference in adoption of preventive behaviors

observed in this study among adults based on income settings. The results of our study further

suggest that education and affordability might play important roles in personal and social

behavior choices adults make to minimize risk of infectious disease transmission to and from

themselves. It also underscores the importance of tailored educational and promotional strate-

gies for dissemination and widespread adoption of preventive measures and implementation

of public health policies [25]. Coordinated social marketing campaigns rather than single-

strategy communication campaigns, going beyond health messages alone, have been reported

to motivate behavior change to reduce the spread of infectious disease on a university campus.

This is stated with the caveat that these changes are sometimes difficult to achieve in commu-

nity or population-based campaigns [27].

We observed in our study that females were more likely than males to adopt each preventive

behavior studied. Gender differences in washing hands with soap before and after touching

potentially infective material or surfaces and use of gloves to prevent influenza transmission

have been previously reported [25].

Beyond vaccination, the addition of preventive behaviors might be a critical tool to help

reduce or slow the spread of influenza. Despite national awareness campaign efforts, influenza

Preventive behaviors used to avoid catching or spreading influenza to others in United States

PLOS ONE | https://doi.org/10.1371/journal.pone.0195085 March 30, 2018 12 / 16

vaccination promotion activities, and events undertaken by CDC to educate the general popu-

lation about the importance of influenza vaccination in collaboration with national and grass-

roots partner organizations [3,28,29], this study like others [17] found that non-Hispanic black

and Hispanic adults are less likely to get the seasonal influenza vaccination as a preventive

behavior. This finding suggests that hesitancy in influenza vaccine acceptance and uptake still

exists among minority race/ethnicities and underscores the fact that continued and sustained

efforts are needed to increase uptake of influenza vaccination by addressing underlying differ-

ences in motivation and barriers across racial/ethnic populations [17].

The findings are subject to several limitations. First, responses to the survey might be sub-

ject to recall bias because they were collected by self-report and vaccination was not verified by

medical records. However, self-reported influenza vaccination status among adults has been

shown to be sensitive and specific [30–33]. Second, the reported preventive behaviors might

not necessarily equate to the performance of such behaviors. Whether or not the respondent

actually performed the behavior(s) was not (could not be) validated by observation. Thus,

responses might be subject to social-desirability bias. Third, the sample was based on respon-

dents who self-select to participate in the Internet panel and agree to participate in the NIFS

through an invitation that references influenza vaccination. Estimates obtained from this

study might be biased if the participation processes (panel and NIFS) were related to receipt of

vaccination. This may not be corrected through weighting. Fourth, the NIFS survey was con-

ducted in English only, which might have resulted in nonrepresentation of those who speak

other languages [17]. Fifth, because the sample was limited to non-institutionalized civilian

adults, generalization is not possible beyond this population. Sixth, we observed that, among

those vaccinated, only 89% said that vaccination is a behavior they use to avoid catching influ-

enza. Among the unvaccinated, about three-fourths said vaccination is a preventive behavior

they use; however, respondents indicated they were not vaccinated. This discrepancy could at

least partially be explained because the survey was conducted early in the influenza season and

these participants might have planned to get vaccinated later in the season. Seventh, we con-

ducted a bias analysis to determine the influence of nonresponse in the results using demo-

graphic and geographic information available in the KnowledgePanel 1

sampling frame. Tests

for the smallest race/ethnicity group (non-Hispanic other/multiple category) showed the high-

est detectable levels of bias, most falling below substantively meaningful levels of 10 percentage

points, indicating that release of additional sample might be needed during the conduct of the

NIFS and changes to the weighting methods. Eighth, none of the behaviors to avoid catching

influenza or to avoid spreading influenza were operationally defined to the participants taking

the survey. Therefore, substantial variation in the interpreted meaning of these behaviors by

the respondents could exist. Finally, though we controlled for some known variables in this

study, there might be unknown confounders that were not controlled for that might have

biased the study estimates, the extent of which is hard to estimate.

Conclusions

The findings from this study identify the frequency with which recommended preventive

behaviors to avoid catching influenza or spreading influenza to others have been adopted by

adults in the United States.

Identifying the current usage of these preventive behaviors provides public health officials

with critical information that can be used to tailor interventions to help reduce or slow influ-

enza transmission. Further research is needed to better understand the role and impact of pre-

ventive behaviors adopted by adults on influenza transmission, and to better understand the

motivation and/or reasons for choosing particular preventive behavior(s) over other(s).

Preventive behaviors used to avoid catching or spreading influenza to others in United States

PLOS ONE | https://doi.org/10.1371/journal.pone.0195085 March 30, 2018 13 / 16

Acknowledgments

The authors thank James A. Singleton and Stacie M. Greby for their thoughtful review of the

manuscript.

Author Contributions

Conceptualization: Anup Srivastav, Tammy A. Santibanez.

Data curation: Anup Srivastav, Tammy A. Santibanez.

Formal analysis: Anup Srivastav, Tammy A. Santibanez, Peng-Jun Lu, Jill A. Dever, Michael

Bostwick, Marshica Stanley Kurtz.

Funding acquisition: Walter W. Williams.

Investigation: Anup Srivastav, Tammy A. Santibanez, Peng-Jun Lu, M. Christopher Stringer,

Jill A. Dever, Michael Bostwick, Marshica Stanley Kurtz, Walter W. Williams.

Methodology: Anup Srivastav, Tammy A. Santibanez.

Project administration: Anup Srivastav, Walter W. Williams.

Resources: Anup Srivastav, Walter W. Williams.

Software: Anup Srivastav, Walter W. Williams.

Supervision: Anup Srivastav, Walter W. Williams.

Validation: Anup Srivastav, Tammy A. Santibanez, Peng-Jun Lu, M. Christopher Stringer, Jill

A. Dever, Michael Bostwick, Marshica Stanley Kurtz, Noreen L. Qualls, Walter W.

Williams.

Visualization: Anup Srivastav, Tammy A. Santibanez.

Writing – original draft: Anup Srivastav.

Writing – review & editing: Anup Srivastav, Tammy A. Santibanez, Peng-Jun Lu, M. Christo-

pher Stringer, Jill A. Dever, Michael Bostwick, Marshica Stanley Kurtz, Noreen L. Qualls,

Walter W. Williams.

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