You may be among the more than 95 million people in the United States who have taken at least one dose of a coronavirus vaccine. Or you may still be awaiting your turn. Regardless, there's a crucial question on most of our minds: How long will the vaccine really protect us?
As with most aspects of the virus, the answer is not completely clear. Why? Because although we have been battling the pandemic for more than a year, the vaccines were granted emergency use authorization relatively recently. So experts have not had time to observe their long-term effectiveness.
However, that research is underway, and in the meantime, experts say we can make an educated guess.
Can we extrapolate from what we know about natural immunity?
In fact, much of this hypothesizing comes from extrapolating data examining immune responses in people who have had covid-19 and illnesses from other coronaviruses, rather than in people who have been vaccinated, said Dbeibo, who is director of vaccine initiatives for Indiana University.
"But vaccine responses should not be less reliable than in natural infection," she added.
Current research shows that people who have been infected with covid-19, the illness caused by the coronavirus, retained immunity that was robust after eight months. That gives researchers a starting point in predicting how long immunity may last after vaccination, Dbeibo explained.
But research also shows people who had more severe cases developed a stronger immune reaction than those with milder forms of the disease. And because vaccine-induced immunity appears to be more similar to natural immunity that is derived from severe covid-19 infections, researchers say they believe people who take a coronavirus vaccine will be protected better than most people with natural immunity, said David Topham, a professor of microbiology and immunology at the University of Rochester.
All of that said, antibodies will wane. And although it is a gradual process, once antibodies decline to a level that is no longer protective, reinfection is possible. Still, the infection is likely to be milder, experts said.
Topham, founding director of the Translational Immunology and Infectious Disease Institute at the University of Rochester, has been studying the coronavirus and the role of memory B cells — immune cells that persist for a lifetime and produce antibodies when re-exposed to a pathogen that they have been programmed to fight. He said some people who were hospitalized with severe covid-19 infections still had high frequencies of memory B cells, as well as antibodies, up to nine months after infection.
He said memory B cells can even adapt quickly to a new variant, usually within days.