RSV vaccine shows promise for infants and seniors, but scientists urge monitoring for nervous system condition.

Pfizer's RSV vaccine for older adults was found effective in preventing lower respiratory tract illness in adults ages 60 and older without any evident safety concerns, except for two cases of Guillain-Barre syndrome. Scientists have called for close monitoring of the vaccine for a possible link to the nervous system disorder. The FDA has asked Pfizer to include Guillain-Barre as an "important potential risk" of the vaccine and develop a safety study to monitor for potential cases if the shot is approved in May.