Episode #23 - I am vaccinated, what next?

VGS   If you've been vaccinated and have questions like when does immunity kick in and how long will it protect you and others? Today, we'll try to answer some of those questions in Science in 5. Welcome, I'm Vismita Gupta-Smith and this is WHO's conversations in science. And answering your questions today is Dr. Katherine O'Brien. Welcome, Kate.

KOB   Thank you so much. Pleased to be with you.

VGS   Kate, after one has been vaccinated, when does the immunity kick in and how long does it last?

KOB   The vaccines that we have right now are all two-dose vaccines. After the first dose, we see a good immune response that kicks in within about two weeks of that first dose. And it's really the second dose that then boosts that immune response and we see immunity get even stronger after that second dose, again within a shorter period of time after after the second dose. We don't know yet how long immunity lasts from the vaccines that we have at hand right now. We're following people who have received vaccinations to find out whether or not their immune response is durable over time and the length of time for which they're protected against disease. So we're really going to have to wait for time to pass to see just how long these vaccines last.

VGS   Kate, after one has been vaccinated, can one still catch COVID-19 and can one also infect others?

KOB   That's a great question. The clinical trials demonstrated that these vaccines protect people against disease. What we don't know yet from the clinical trials is whether or not the vaccines also protect people from just getting infected with the SARS-CoV-2 virus and whether or not it protects against transmitting to somebody else. So, this is a really important part of our understanding about what these vaccines do. Do they only protect against disease or do they also protect against getting infected and being able to transmit to somebody else, even if you're not having any symptoms?

VGS   Kate, explain to us, why does one need to continue with the precautions even after vaccination? And, how long are we expected to take these precautions?

KOB   So, we really need to continue these precautions while we're still learning about what the vaccines can do. Can they protect against getting infected and transmitting to someone else? And right now, we're in a situation where there's still very broad transmission in many countries, the transmission is just out of control. And so for how long we need to continue these precautions is really going to depend on what communities and countries can do to really crush this virus, to crush the transmission. And in that way, the vaccines can do their their best job at preventing disease. But remember that we don't actually have the evidence yet for using the vaccine in some age groups. We don't have the evidence for use of vaccines in children, for instance. So for the time being, those age groups are going to continue to be at risk of both disease and infection and being able to transmit to other people. The second reason is that the vaccines are in short supply, so we don't have enough vaccine yet out in the community to protect everybody. Those are the reasons why we have to continue the precautions, especially the masking, the physical distancing, the hand washing and not gathering in big groups. For how long we need to continue those those interventions? Time is going to tell. Once we get broad vaccination coverage in the community, when we know more about what the vaccine can actually do to prevent infection, and we can slowly start taking our foot off the pedal of these other interventions and make sure that the transmission, again, doesn't start to escalate again.

VGS   Thank you, Kate. That was Dr. Katherine O'Brien. We’ll continue to answer your questions about vaccines and immunity and about COVID-19 in this series. If you found this information useful, please share it with your networks. Until next time then. Stay safe, stay healthy and stick with science.