Interviewer: Professor Peter Smith, thank you very much for
taking the time to do this interview with us today to
discuss testing future vaccines against COVID-19 using human challenge trials.
Let me jump right in and ask you about the human challenge trials themselves.
What are they and how do they differ from classical human trials?
Prof. Smith: Perhaps it's best to say what classical trials are first, normally
in the end stages of testing a vaccine to see if it actually protects against disease,
a very large number of people are vaccinated
and a similar number of people are given a placebo injection.
Those individuals are decided at random,
(who gets the vaccine, who gets the placebo),
and then they're followed to see which ones develop (in this case COVID) disease,
and the length of the trial
depends on how long it takes sufficient numbers of people to develop COVID disease,
to be able to tell if there's a difference between those who
received the vaccine and those who received the placebo.
What's uncertain is just how long
such trials will take in the present circumstances, where many people
(most people) are doing all they can to avoid infection.
What we've suggested in terms of an alternative way of
evaluating vaccines is to undertake human challenge trials where
a small number of people are recruited who are fully informed