Now there are three. Moderna Inc. has posted strong phase III study data on its mRNA respiratory syncytial virus (RSV) vaccine, keeping pace with Pfizer Inc. and GSK plc’s candidates, which have May PDUFA dates. Moderna’s top-line results of the ConquerRSV pivotal efficacy study of mRNA-1345 show the vaccine hit its primary efficacy endpoints of 83.7% against RSV-associated lower respiratory tract disease in older adults.