However, challenge trials will need to answer many questions before nations give the go-ahead.
Covid-19’s full spectrum of impact on the physiology, the degree of severity of this, etc, are still not clear.
Covid-19’s unprecedented health effects and the way this has scrambled socio-economic functioning have fanned anxiety over finding a pharmacological intervention. Several proposals of “challenge trials” that involve deliberately infecting trial participants to study the efficacy of vaccines/preventatives that they have been administered have been made, but haven’t been seriously pursued given the medical and ethical minefield such decisions have to traverse.
Now, the UK government has announced the first-ever challenge trial, to be rolled out in January 2021 once it receives final regulatory and ethical approval, Nature reports. The aim is to fast-track vaccine development. Proponents pointed to the potential benefits—fast-tracking a successful vaccine by just a month, it has been estimated, can prevent the loss of 720,000 years of life globally (in terms of expected life-span if the lives factored for this calculation are not ended by Covid-19). Besides, challenge trials have provided a wealth of knowledge on influenza and malaria, both serious killers.
However, challenge trials will need to answer many questions before nations give the go-ahead. Given how these challenges require low-risk participants, they may not really give much insight about vaccine efficacy. Indeed, even the phase III trials don’t have too many older participants, but they at least have a few. That apart, Covid-19’s full spectrum of impact on the physiology, the degree of severity of this, etc, are still not clear. In such a scenario, it is difficult to say for sure that informed consent can be given. These are considerations that the UK, Belgium and the US, which have talked about human challenge trials, must keep in mind.