RSV VACCINES FOR KIDS HAVE A CHECKERED HISTORY: FDA Advisors Say More Data Needed for RSV Vaccines in Young Kids: A “very complicated situation” after mRNA vaccine trial was halted, expert says. “FDA advisors said that more data are needed to fully understand if there are broader safety concerns related to use of respiratory syncytial virus (RSV) vaccines in young children after an mRNA vaccine trial was halted earlier this year. Moderna, which had been developing an mRNA vaccine candidate for RSV in infants and toddlers, notified the FDA in July that it had paused a phase I trial due to an imbalance of severe/hospitalized RSV cases in RSV-naive infants ages 5 to 7 months who had received the vaccine versus placebo, raising concern for possible vaccine-associated enhanced respiratory disease (VAERD), according to FDA briefing documents.”

An earlier effort at RSV vaccine had a similar problem.