Will Americans have the right COVID vaccine this fall?

In a few short months, the weather will turn crisp, the holiday season will draw near, and the coronavirus may embark on its third consecutive winter of death and devastation.

That prospect has federal regulators and their scientific advisers engaged in a high-stakes guessing game.

The question: How should the COVID-19 vaccine change?

Certainly, the circumstances have changed. The coronavirus strains responsible for 97% of infections today — BA. 4, BA. 5 and BA. 2.12.1 — didn’t exist in 2021, let alone in 2020. Yet all of the vaccines currently available in the U.S. are designed to recognize the version that left China in January 2020.

The shots have done an admirable job. Researchers credit them with saving 1.9 million U.S. lives in their first year of availability, and they continue to provide solid protection against severe illness and death from COVID-19. The ubiquitous omicron subvariants, however, have several mutations on their crucial spike proteins that make them less recognizable to an immune system primed to fight the 2 1/2-year-old virus.

The result: A real-world study found that the protection from three doses of mRNA vaccine is half as strong against omicron compared to the Delta variant that preceded it.

At the end of June, the FDA asked vaccine manufacturers to produce “bivalent” doses that combine the original vaccine with one designed to recognize BA. 4 and BA.5. Who will be advised to get it has yet to be determined.