Gavi works to expand access to vaccines for children in some of the world’s poorest countries. Health experts say the move could have deadly consequences.

Robert F. Kennedy Jr. has repeated that not enough childhood vaccines have been tested in clinical trials against a placebo.

The preservative thimerosal has been removed from all but a few vaccines, and studies have confirmed no link to neurodevelopmental issues including autism. So public health experts were puzzled when it appeared on the agenda for this week’s meeting of outside vaccine advisers to the US Centers for Disease Control and Prevention.