“Everybody wants to know about the boosters, when it's needed, how often it's going to be needed and so on. There are many factors that can influence this. One is the type of vaccine. We know that each vaccine has a slightly different performance and longer follow up is telling us the efficacy of the vaccines, particularly in preventing severe disease but also in preventing infection. The other big variable of course is, the variants of the virus that we are seeing. And we've seen that different variants have different abilities to be neutralized by the antibodies, or be able to overcome the immune response, like Omicron seems to be doing because of the mutations it has it seems to be pretty good at evading immune responses. The third factor of course is the biology of the individual, the age of the person, how strong the immune system is, whether there are other underlying illnesses which impact the immune system. And therefore when we make recommendations for a course of vaccination, we have to take into consideration all of these factors. There is some data now to show that there is a slippage in the protection due to the different vaccines at about six months or so, particularly for protection from infection, less so for protection from disease; they are still performing at 80%. But with Omicron again, the initial data coming in obviously showing that Omicron is very successfully able to evade immune responses and therefore needs higher levels of antibodies. For now we believe that boosters may be needed for people who have weaker immune systems, the older individuals, the more vulnerable people and whether a third dose of the vaccine is going to be it, or whether they are going to be need for additional vaccines like influenza every year, every couple of years, it's too early to say and we need to really follow the science on that.”

by: Soumya Swaminathan