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4. Whether priority should be given to prevention or treatment.
Numerous challenges face clinical trials taking place in outbreak situations. In this scenario, decision on whether priority should be given to prevention or treatment is crucial. In developing the guidelines for WHO coordinated response, it is recommended that priority be given to treatment for various reasons.
First, since the discovery is new, there may be a number of unknowns regarding vaccination. For example, the durability and rapidity of immune responses is unknown. Rapidity of an immune response is important because it determines the relative effectiveness of the vaccine in the context of ring vaccination. Ring vaccination strategy has been shown to be effective in preventing new cases and limiting the spread of infectious diseases. Therefore before prioritizing TropicX as vaccine, more research is needed in the area of efficacy and immunogenicity.
Another unknown regarding TropicX as a vaccine relates to adverse events. Although few serious vaccine-related adverse events have been observed, additional large-scale trials need to determine the overall safety of new vaccines (Levy et al, 2018). For example, one of the Ebola vaccine (rVSV-ZEBOV) has been shown to be a risk factor in the development of arthritis to females who have a medical history of arthritis (Levy et al, 2018).
As such, there may also be challenges in administering the vaccine. In an outbreak context, it may be easily interpreted the vulnerable group, children and pregnant women, receive every possible protection from the disease. But since these two groups are seen as particularly vulnerable, they should not be placed on the “front line” of interventions that have yet to be fully tested. Therefore excluding them from the vaccines may raise ethical concerns.
The final unknown relates to community engagement and ongoing trust-building throughout the vaccine process which are crucial. Distrust towards vaccines might exist in the population and negatively affect cooperation with the vaccine administration or even lead to suspension, as occurred in Ghana, where two Ebola vaccine trials were suspended because of negative rumours ( Kummervold et al, 2017).
In addition, the affected population may also not accept the vaccines particularly when the research is led by foreign institutions or personnels. For example, the current outbreak of Ebola in DRC, ring vaccination of those who fall ill and their contacts has not succeeded in limiting the spread of the virus because there is mistrust of the vaccine (www.theguardian.com, 2019). Some people falsely believe that Ebola vaccine is what is making people sick (www.theguardian.com, 2019). Hence there maybe confusion and mistrust since the vaccine is new.
Finally, since the supply of TropicX is limited, managing the demand for vaccine intervention will be challenging. Limited supply of the vaccine means denying somebody the right to an intervention which might be effective. This may raise questions especially in this situation where the case fatality rate from the disease is high.
Thus, priority should be given to treatment because it provides the greatest possible benefit for participants under imminent threat of the disease. Treatment also provides optimal care to patients already suffering the disease. To wrap it up, in absence of approved vaccines, control of the epidemic should rely on treatment or on nonpharmaceutical interventions such as quick identification and isolation of cases.
Reference
The guardian, 2019. DRC Ebola epidemic is international emergency, says WHO https://www.theguardian.com/world/2019/jul/17/drc-ebola-epidemic-is-international-emergency-says-who
Kummervold PE Schulz WS Smout E Fernandez-Luque L Larson HJ Controversial Ebola vaccine trials in Ghana: a thematic analysis of critiques and rebuttals in digital news. BMC Public Health. 2017; 17: 642
Lévy Y, Lane C, Piot P, Beavogui AH, Kieh M, Leigh B, et al. Prevention of Ebola virus disease through vaccination: where we are in 2018. Lancet (London, England). Elsevier; 2018;392: 787–790. pmid:30104048