EXPLAINER: Are we going to need COVID-19 booster shots?

Just because Pfizer wants to offer COVID-19 vaccine boosters doesn’t mean people will be lining up anytime soon -- U.S. and international health authorities say that for now, the fully vaccinated seem well protected.

Globally, experts are watching closely to determine if and when people might need another shot. At the same time, many suggest the priority for the time being should be vaccinations, noting that worrisome coronavirus mutants wouldn’t be popping up so fast if more of the U.S. and the rest of the world had gotten the initial round of shots.

“If you want to stop hearing about the variant of the week,” said Jennifer Nuzzo, a Johns Hopkins University public health specialist, “we need to do more work to make sure all countries have more access to vaccines.”

Here are some questions and answers about vaccine immunity and boosters.

WHAT’S PROMPTING ALL THE BOOSTER DEBATE?

U.S. health officials have long said that people one day might need a booster -- after all, they do for many other vaccines. That's why studies are underway to test different approaches: simple third doses, mix-and-match tests using a different brand for a third dose, or experimental boosters tweaked to better match different variants.

But last week, Pfizer and its German partner BioNTech announced that in August, they plan to seek Food and Drug Administration authorization of a third dose because it could boost levels of virus-fighting antibodies, possibly helping ward off worrisome mutants.

The companies haven't publicly released data, and U.S. health officials issued a sharp response that boosters aren't yet needed and that the government, not vaccine makers, will decide if and when that changes.

The World Health Organization said Monday there is not enough evidence to show that third doses...