http://www.newsweek.com/cdc-director-booster-advice-counter-waning-protection-fourth-dose-pfizer-israel-1695466

People should use their own judgement to decide when is best for them to get a second COVID booster vaccine, Rochelle Walensky, director of the U.S. Centers for Disease Control and Prevention (CDC), has said.

Last week, the CDC recommended second booster doses—a fourth shot for many people—for certain immunocompromised individuals and people over the age of 50 as long as they had received their initial booster dose at least four months prior.