Can you count on your Covid vaccine to keep you safe?

Real-World Data For All Vaccines Is Very Encouraging. Some Are Not So Good At Stopping Infection, But Even They Prevent Serious Illness

China’s latest outbreak started in Nanjing with the arrival of a Covid-positive passenger from Moscow, on July 10. As the case count rose, Chinese authorities were surprised that “many of the early Nanjing cases were people who were fully vaccinated,” a BBC report says. As word spreads, vaccinated Chinese might wonder if their shots are any good.

In India, the latest serosurvey shows that “about 10% of individuals who got both vaccine doses showed no antibodies,” eminent virologist Shahid Jameel wrote in TOI on Thursday. Should you doubt your vaccine’s usefulness then?

At the start of 2021, Covid vaccines were approved for the public with efficacy figures ranging from 65% to 95%. Eight months on, what does the real-world data say – are vaccines effective or not?

Time to forget about efficacy percentages

Remember how a bike maker used to claim 81kmpl mileage “under ideal test conditions”? Similarly, efficacy is “the degree to which a vaccine prevents disease, and possibly transmission, under ideal and controlled circumstances,” Linda Geddes explains in an article for Gavi, the global initiative for equitable vaccine distribution.