Tens of thousands of people are rolling up their sleeve every day to get the COVID-19 vaccine. India presently has three COVID-19 vaccines available — Covishield, Covaxin and Sputnik V, which are all two-dose vaccines. As of May 28, the Union government has recommended that the gap between two doses of Covishield be 12-16 weeks apart, while Covaxin be administered 4-6 weeks apart and Sputnik V 21-90 days apart.
Experts say that it is only two weeks after the second dose is administered that an individual can be considered fully vaccinated. But once you have been vaccinated with both doses, how long will this immunity last? The World Health Organisation’s Dr Katherine O'Brien said that a good immune response kicks in about two weeks after the first dose but it's only the second dose that boosts this, making a person’s immunity even stronger. But just how long this immunity lasts is still unclear.
“We don't know yet how long immunity lasts from the vaccines that we have at hand right now. We are following people who have received vaccinations to find out whether their immune response is durable over time and the length of time for which they are protected against the disease. So we are really going to have to wait for time to pass to see just how long these vaccines last,” said Dr Katherine.
However, what we do know is that based on ongoing trials from Pfizer, the two-dose vaccine remains effective for at least six months, perhaps longer. People who received the Moderna vaccine were also found to have antibodies six months after the second shot. Oxford-AstraZeneca, which is known in India as Covishield, also says, “At this point, we cannot say, but other vaccines using the Oxford ChAdOx1 technology are proven to provide immune responses that can persist for a year or more.”
With new variants of the COVID-19 virus emerging and with vaccines being less effective among some strains, experts say a third booster shot will be required, followed up perhaps by annual revaccination.
And although there is still much we are learning about COVID-19 vaccines, two recent studies have found that immunity to the coronavirus lasts at least a year, possibly a lifetime, especially after vaccination. This means that persons who have recovered from COVID-19 and were later fully immunised will not need a booster shot, reported The New York Times.
It is, however, recommended that those who have been immunised continue to mask up, maintain physical distance and adhere to other COVID appropriate behaviour.