Bivalent Covid-19 Vaccines — A Cautionary Tale

Fortunately, SARS-CoV-2 variants haven’t evolved to resist the protection against severe disease offered by vaccination or previous infection. If that happens, there will be a need to create a variant-specific vaccine. Although boosting with a bivalent vaccine is likely to have a similar effect as boosting with a monovalent vaccine, booster dosing is probably best reserved for the people most likely to need protection against severe disease — specifically, older adults, people with multiple coexisting conditions that put them at high risk for serious illness, and those who are immunocompromised. In the meantime, it is believed it would be better to stop trying to prevent all symptomatic infections in healthy, young people by boosting them with vaccines containing mRNA from strains that might disappear a few months later.