What We Know So Far About Covid-19 Immunity -- And What It Means For Vaccine Boosters


Since the start of the pandemic, scientists have been seeking to better understand immunity to the novel coronavirus. How long is a person immune after having Covid-19, after getting vaccinated, or both? And what could long-lasting immunity mean for booster shots?

It's still too early to tell -- but experts are getting closer to cracking the code.

The current wisdom around potential coronavirus vaccine boosters suggests they may be needed at some point -- but exactly when is unclear, Dr. Peter Marks, director of the US Food and Drug Administration's Center for Biologics Evaluation and Research, said on Thursday during a Covid-19 Vaccine Education and Equity Project webinar.

"We'll have to see where this all interacts. Is it possible we're going to need a booster at some point? Yes. Is it probable? Yes. Do we know exactly when? No," Marks said. "But if I had to look at my crystal ball, it's probably not sooner, hopefully, than a year after being vaccinated, for the average adult."

And, experts emphasize, anyone who is fully vaccinated currently should still be protected. But the reason why the timeline for potential boosters remains unclear is because scientists still need time to collect the data on how long immunity against Covid-19 may last in the future -- and how to factor in future variants.

When a person has "immunity," in general, that means they have protection against a disease. Active immunity can be acquired either through vaccination or infection. Your immune system develops antibodies either induced by the vaccination or in response to the infection -- and either immune response can maintain a "memory."

Immunity is often measured by the presence of antibodies -- proteins made by the immune system to help fight infections, in the blood. They can usually be determined with a laboratory test. But immune systems are much more than just antibodies; they involve a host of players including B cells, which produce antibodies, and T cells, which target infected cells.

Research has shown that both antibodies and T cells might even recognize infections from variants of a pathogen -- such as the emerging coronavirus variants circulating in the world today, which, despite key differences that may make them spread more easily, have enough similarities to be recognized by the immune system's memory.

And even if someone recovered from a previous infection and has a natural immunity, vaccinations can help give their immune memory a boost.