COVID-19 shots might be tweaked if variants get worse

The makers of COVID-19 vaccines are figuring out how to tweak their recipes just in case the shots need an update against worrisome virus mutations. But changing the recipe is just one step. Harder is deciding if the coronavirus has mutated enough to update vaccines — and if so, how. Flu vaccine is reformulated just about every year, and authorities are looking to that system as a blueprint. Viruses always mutate, and one key step will be better tracking to target only the variants that really threaten the COVID-19 vaccines’ effectiveness.