The vaccines being used in the United States and other parts of the world are safe and effective in preventing severe cases of COVID-19.
How long that protection lasts is still not fully understood — both the virus and the vaccines against it are relatively new.
Breakthrough infectionsTrusted Source — those occurring in people who have been vaccinated against COVID-19 — are happening.
So far, though, they are largely occurring without major problems. Most people are asymptomatic, and their cases are discovered only during routine testing.
As variants of the novel coronavirus continue to spread and mutate, researchers are monitoring how the vaccines perform and whether booster shots will be needed to maintain meaningful immunity.
Right now, experts say it’s too early to speculate whether we’ll need booster shots like some routine vaccines.
Dr. Amesh Adalja, a senior scholar at Johns Hopkins Center for Health Security in Baltimore, says it’s premature to predict whether COVID-19 boosters will be needed and, if so, at what intervals.
“To me, the threshold for boosters would be to see fully vaccinated individuals getting breakthrough infection severe enough to land them in the hospital,” Adalja told Healthline. “We have not crossed that threshold.”
However, the CEO of the companies whose COVID-19 vaccines are being distributed in the United States say their shots may need to be given annually, like a flu shot. They told Axios those boosters could come as early as September.
Data shows Moderna and Pfizer vaccines, which both use the same mRNA technology to create immunity against the novel coronavirus, remain effective after 6 months.
Still, Pfizer officials in February said they are testing a booster shot up to a year after a person receives their first two doses.
AstraZeneca’s vaccine — which hasn’t received approval to be used in the United States — has been tested with a boosterTrusted Source or a second shot after 12 weeks.
Still, it doesn’t appear to offer any more meaningful protection than doses given closer together.
An international team of researchers published a paperTrusted Source in the journal Nature Medicine in January that looked at what was next for COVID-19 vaccinations beyond their phase 3 trials.
“Additional booster doses might be necessary to extend the duration of protection,” they wrote. “We do not know whether primary series and booster doses can or should be different.”
Dr. Anthony FauciTrusted Source, the United States’ leading voice on infectious diseases, told a Senate subcommittee last week that he doesn’t anticipate that the durability of the COVID-19 vaccine protection “is going to be infinite.”