Episode #25 - Vaccines explained

11 February 2021 | Science conversation

Vismita Gupta-Smith

Hello and welcome to Science in 5. I'm Vismita Gupta-Smith and this is WHO's conversations in science. We're going to continue our conversation on COVID-19 vaccines and explaining the science and evidence behind it is WHO's Chief Scientist Dr. Soumya Swaminathan. Welcome, Soumya. 

Dr. Soumya Swaminathan

Thank you, Vismita.

Vismita Gupta-Smith

Soumya, we're going to start with a question that we get quite often. If I have already had COVID-19, do I still need to be vaccinated?

Dr. Soumya Swaminathan

We know that most people who have COVID-19 do develop an immune response, but there is a subgroup of people, particularly those who have had very mild infection and sometimes they don't even know it, you know, it's asymptomatic. Those people we know have a less strong immune response compared to those who have been seriously ill and, you know, get good antibody response. So in general, we are now recommending that people should get a vaccine if they fall into that priority group, regardless of the fact whether they have had a previous infection or not. And the good thing is that, you know, the immune system recognizes the same antigen, the same protein. So even if you've had a previous infection and you now get a vaccine, it acts like a booster and it boosts that immune response, both the antibody response as well as the T cell response. And so you're much more assured that you have a good immune response and that it's going to last for a long time. Of course, how long this immunity is going to last is something that researchers are still looking at. We don't know the answer to that. But at this point, we do recommend that you get a vaccine. Whether or not you've had a previous infection. 

Vismita Gupta-Smith

Soumya, another common question that we're getting is that the current batch of vaccines against COVID-19 is not for children under 16. What is the reason and the science behind that?

Dr. Soumya Swaminathan

So whenever new drugs or vaccines are developed, they go through this clinical trial, right? The testing in people with the disease in order to make sure that they are both safe and effective. And this usually starts with adults, because in case there is an unexpected side effect that we don't know about, we don't want children to be the first ones exposed. So, all the vaccines that have been developed so far have been tested in people over the age of 18 years or in one case 16 years. And so that's the population for which there is data. That's the population for which these vaccines are being recommended. Because COVID-19 is a much more serious and deadly disease in older people, all the developers have ensured that older people and people with underlying diseases like hypertension, diabetes and heart disease have been included. So that group we know that this vaccine works and it's safe, the ones that are getting approvals. The studies in children will be starting soon. And in the next coming months, we will get more data on children. Also, supplies are limited. Global supplies of vaccines are limited, are being targeted to those at highest risk initially. So by the time we get the data on children, there's more vaccines to go around. We will then make the guidelines for vaccination in children. But as of now, vaccines are for people above the age of 18 years.

Vismita Gupta-Smith

Soumya, in my family, my elderly mother has been vaccinated because she's in the high risk group. One of the common questions that I get and we also see on our timelines is what are the common side effects of the current batch of vaccines? Also, when should one call one's doctor after vaccination?

Dr. Soumya Swaminathan

So, what happens when you go in for vaccination into a into a clinic is that you take your vaccine and then you're asked to wait. This is because the health care providers there want to watch you. Very rarely, you might have an allergic reaction, but if you're in the clinic, they can take care of it. So that's why you're asked to wait. Beyond that, you may have, you know, common symptoms after vaccination are usually a pain or soreness or redness or swelling in the arm at the site of the injection, you might get a low grade fever, body ache or a headache or just not feeling too good. And this is expected because it's the body's immune system reacting to this antigen that's been put into the into the body and the immune system is gearing up to fight. So that's quite common. It usually last two or three days, not more than that and then you're, you know, feeling absolutely fine. Going beyond the first three or four days, if you develop anything unusual or if any of these symptoms are persistent or you have other unusual symptoms that you don't normally have, then it might be worth going and reporting to the same place where you got your vaccine or if you've got a mobile app, you could do it through that because it's important that we track people who have been receiving these vaccines and record any unusual side effects that may occur.  And we are collecting a global database now. The good thing is that, till today, about 100 million vaccine doses have been deployed worldwide just in the last two months, and so far there have been no big warning signs or red flags. But we do need to continue that follow up and the data so, you know, report back if anything unusual is going on, but expect some mild side effects, which would last for a few days. 

Vismita Gupta-Smith

Thank you, Soumya. That was WHO's Chief Scientist, Dr. Soumya Swaminathan. Until next time, then. Stay safe, stay healthy and stick with science.