How long do the effects of COVID-19 vaccines: Do you need a third booster shot

New Delhi, June 08: India on Monday announced that it was changing its vaccination policy. In his address to the nation, Prime Minister, Narendra Modi announced that the Centre would vaccinate the entire population above the age of 18 free of cost and states would no longer have to take the burden of the same.

India currently has three vaccines-Covishield, Covaxin and Sputnik V. All are two dose vaccines and in the case of Covishield the Centre recommended the gap between the two doses at 12-16 weeks. In the case of Covaxin, it is 4-6 weeks while in the case of Sputnik V, it is 21-90 days. While a person is considered to be fully vaccinated only after taking the second dose, the question is how long does the effect of a vaccine last.

Time to build immunity:

According to Dr Katherine O' Brien of the World Health Organisation, after the first dose, a good immune response kicks in after about two weeks. However after the second dose, the immunity boosts further, following which the immune system becomes much stronger.

How long do effects of vaccines last:

While it is unclear how long the immunity post the vaccination lasts, Dr. Katherine said that it would take time for them to know exactly. We are following people who have received the vaccinations to find out whether their immune response is durable over time and the length of time for which they are protected against COVID-19. Hence we really have to wait for time to pass to see how long these vaccines last, she also said.
In the case of Pfizer, it is said that the effects last around 6 months or slightly longer. In Moderna, it was found to have had anti-bodies for six months after the second dose. In the case of Covishield it is said that the effect would last for a year or more. Dr. Katherine says while at this point nothing much can be said, in the case of other vaccines using Oxford ChAdOx1 technology, it is proven to provide immune responses for a year or more.

Do you need a booster dose?

The efficacy of the vaccines against the B.1.617.1 and B.1.617.2 variants are now in question. Scientists have said that a third booster dose would be needed in this case. The manufacturers of Covaxin, Bharat Biotech said that it has already started trials for a booster dose. The booster dose would be given six months after the participants had received their second dose in the trial stages that had taken place in September and October 2020.

However there are studies to show that the immunity to COVID-19 after the two doses last at least a year. It also showed that a person who is recovering from COVID-19 and is later fully immunised, he will not need a booster shot at all.