In more than 4,000 people, preexisting antibody patterns predicted responses to COVID-19 vaccination, with higher levels of antibodies to common microbes associated with stronger responses, suggesting past immune encounters may reveal a person’s baseline vaccine readiness.

In more than 4,000 people, preexisting antibody patterns predicted responses to COVID-19 vaccination, with higher levels of antibodies to common microbes associated with stronger responses, suggesting past immune encounters may reveal a person’s baseline vaccine readiness.