U.S. regulators have cleared a third updated COVID-19 vaccine for this fall, shots made by Novavax Inc.

Already, Pfizer and Moderna are shipping shots modified to better match more recent strains of the ever-evolving coronavirus. Those doses can be used in adults and children as young as 6 months.

Friday, the Food and Drug Administration gave the OK to the updated Novavax formula, too -- and those shots are open to anyone 12 and older.

While most Americans have some degree of immunity from prior infections or vaccinations or both, that protection wanes. Despite this summer's wave, winter surges of COVID-19 tend to be worse and health officials are urging Americans to get one of the vaccine options this fall.

Novavax makes a protein-based vaccine mixed with an immune booster, a different technology than Pfizer and Moderna's so-called mRNA vaccines.

This year there's another slight difference in the formulations. The Pfizer and Moderna recipes are tailored to a virus subtype called KP.2. The Novavax formula targets its parent strain, called JN.1. The FDA considers both closely enough related to currently circulating strains to offer cross-protection.

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