Episode #13 - COVID-19 - Vaccine trials

Transcript

Vismita Gupta-Smith:

As the world races towards a COVID-19 vaccine, we hear a lot about vaccine trials. Welcome to Science in 5. I’m Vismita Gupta-Smith and we're talking about COVID-19 vaccine trials.And here to explain it all is WHO’s Dr. Katherine O’Brien. Welcome, Kate.

Dr. Katherine O’Brien:

Thank you so much. I'm happy to be with you today.

Vismita Gupta-Smith:

Kate, explain to me Phase I and Phase II of vaccine trials. What are we looking for? What are we testing for?

Dr. Katherine O’Brien:

Phase I trials are the small trials that are the first time that a new vaccine is being evaluated in humans. These would be vaccines that have come out of laboratory development, testing in some animals. And so, Phase I is the first time we go into humans. They're almost always tested in young, healthy adults. And the purpose of Phase I trials, where we're testing usually in tens, perhaps up to a hundred people, is to evaluate the dose of the vaccine to try and get that right. Secondly, to assess whether or not the vaccine is creating any immune response that we're trying to evoke. And, the third is to start accumulating safety data on the vaccine. Phase II trials is the next stage. The number of people who are in Phase II trials is larger than the number who are in Phase I trials. And, we use Phase II trials to start to look at the vaccine in the age group that it's intended to be used in. We're also using Phase II trials to test in a larger number of people the immune response, more details about the immune response to the vaccine. And thirdly, to get a larger database on the safety of the vaccines.

Vismita Gupta-Smith:

Could you please explain the Phase III of vaccine trials? What is it that we're looking for in this phase?

Dr. Katherine O’Brien:

Yes, if a vaccine makes it through Phase I, where it's been shown to have some immune response, and then Phase II, with the right immune response in the right age group and a good safety profile – those vaccines that make it through those two stages, will go on to a Phase III trial. Phase III trials is when a vaccine is tested in a much larger number of people. And the purpose of the trial is, first and foremost, to continue to accrue evidence on safety.  And secondly, is to figure out whether or not the vaccine can actually protect against the disease that it's intended to protect against. Those Phase III trials, as are Phase II trials, are developed in a way where some people get the vaccine and some people get another product that is not the vaccine that's being studied. Sometimes it's called a placebo. And, we compare the disease events in people who got the vaccine and people who didn't get the vaccine. That's how we tell whether or not the vaccine itself is protecting against the disease.

Vismita Gupta-Smith:

So, when we hear about a vaccine trial being halted because someone developed some symptoms or an adverse event happened, what does that mean?

How should we understand that?

Dr. Katherine O’Brien:

I know people are concerned when they hear that a COVID vaccine trial, or any vaccine trial, has been paused. I want to really emphasize that this is actually a standard, normal practice of clinical trials. And they're paused out of an abundance of caution, if there's somebody in the trial who has developed symptoms or an illness – a disease that was either unexpected or is of a significant nature. The reason that the trial is paused is, an evaluation needs to take place of whether it's possible that the vaccine that somebody received, or that they didn't receive a vaccine, and they were in the placebo arm of the study, whether it was related or not related to the product that they received in the clinical trial. So, these are normal parts of a clinical trial and it really shows that the clinical trial is being conducted to the highest standards of safety evaluation and assuring that an earliest look at any possible issues around safety are being looked at really seriously.

Vismita Gupta-Smith:

Thank you, Kate. That was Dr. Katherine O'Brien explaining vaccine trials. Please remember to share this information with your friends and family. Be the source of scientific and evidence-based information for your network. Until next time then. Stay safe, stay healthy and stick with science.