FDA vaccine chief on autumn COVID booster update

COVID-19 vaccines tweaked to better match today's omicron threat are expected to roll out in a few weeks, but it's still unclear how much benefit the booster shots will offer, who should get one and how soon.Pfizer and rival Moderna both asked U.S. regulators this week to authorize modified versions of their booster vaccine.

Dr. Peter Marks, FDA vaccine chief said “By changing the composition of what is in these boosters, we are able to elicit and essentially refresh the immune response so that it will hopefully do a better job of eliminating the virus."

BA.5 currently is causing nearly all COVID-19 infections in the U.S. and much of the world, but current COVID-19 vaccines match the coronavirus strain that circulated in early 2020.While those vaccinations still offer strong protection against serious illness or death from COVID-19, there's little effectiveness against infection from the wildly mutated omicron family.Pfizer and Moderna both studied an earlier tweak to their vaccines that targets the original omicron, called BA.1, that hit last winter, plus even earlier variants.FDA will use data from human testing of the BA.1-tweaked doses plus mice tests of the BA.5-targeted version to decide if the newest update spurs protective levels of virus-fighting antibodies.