COVID vaccine boosters: when you might need one and how the vaccine brand you got plays a role

MADISON, Wis. — If you got a COVID vaccine, you’ve likely been thinking about how long it will last. Many doctors have said booster shots will probably be necessary, but they’re still trying to figure out when that might be.

“In a normal, non- pandemic situation, we’d probably have those answers before the vaccines were rolled out, but we’re not in that situation and we needed to get people vaccinated quickly,” said Dr. William Hartman at UW Health.

He said the data doctors do have shows that Pfizer and Moderna’s vaccines are still at least 90% effective six months after being injected.

Sometime after those six months, a person’s immunity to the virus will drop off. It could be a year after their first shot or even three years later, but enough time hasn’t passed for this to be tested.

Johnson & Johnson is a different type of vaccine.

“With these adenovirus vaccines, it’s possible that the efficacy of the vaccine actually increases as time goes on,” said Hartman.

So if you got Johnson & Johnson’s vaccine, your immunity is likely getting better as time goes on. It will be more effective at three months than it was one month after your shot. So a booster might be needed later than it would be for those who got Pfizer or Moderna.

“I do anticipate all these vaccines kind of having different points where they hit that peak, and then you see a drop in the immunity,” said Hartman. “At some point, is it all going to be one vaccine and everyone can be on the same timecard.”

But variants will always threaten to slow the vaccination process down and require booster shots even sooner. While Pfizer and Moderna have proven to be effective against the UK variant, other variants or new variants could be resistant.

“If say the South African variant came in (to Wisconsin) or the California variant came in, we may need to re look at the boosters in terms of do we need to make a booster against that variant,” said Hartman.

It’s also not known yet if you will need to get the same brand of the booster shot that you did of the original vaccine.