There is now good evidence to suggest that the new, bivalent boosters from Moderna and Pfizer cut infection risk by half from the so-called "Kraken variant" of Omicron, XBB.1.5.

There was much hemming and hawing in the late fall and early winter about early studies that cast doubt on whether the updated, bivalent booster shots that many of us got in recent months were effective at all against the rising, extra-extra-contagious strain of COVID-19 — the XBB.1.5 variant.

While XBB.1.5 has gained majority prevalence in the Northeast, it doesn't appear to be getting traction in the South and West quite as fast as some experts predicted. But once it is here in larger numbers, you'll be glad to know that the bivalent boosters are pretty good at preventing infection as well as severe illness.

As the Chronicle reports, via a new CDC study, the updated Pfizer and Moderna shots protect against symptomatic infection from XBB.1.5 about as well as they protect against symptomatic infection from the variant they were designed for, BA.5 — 48% with the new variant, vs. 52% with BA.5 for those between the ages of 18 and 49. For the age 50 to 60, the new booster protects against either variant being symptomatic between 40% and 43% of the time.

When it comes to severe infection and hospitalization, the figures are likely higher, says one of the study's authors, Dr. Ruth Link-Gelles. "What we know from past experience is generally that the vaccines protect better against more severe disease," Dr. Link-Gelles says. "So these are estimates for symptomatic infection and we would expect that similar estimates for hospitalization and death would be higher."

The CDC estimated last week that XBB.1.5 was responsible for about half of all new infections across the country, up from 37% the previous week.

As for when you might need yet another booster if you've already gotten the bivalent booster, that is sort of up to you once you're a few months out. But the CDC suggests that there might be more longer-term immunity built up when one waits six months or more.

It should be noted, we may have to start paying for our own shots soon.

This week, the FDA will be meeting to discuss putting COVID boosters on an annual schedule, like flu shots, and having annual updates made of the shots based on currently circulating variants. As NBC News reports, the agency will also be discussing a recommendation that the unvaccinated and mostly healthy go ahead and get the new boosters even if they haven't had their initial two-shot series — though the elderly and immunocompromised over the age of 6 will still be encouraged to start with the two-shot series.

Previously: Report: Moderna Wants to Charge $130 Per Dose For COVID-19 Vaccines

Photo: Mufid Manjun