FDA grants breakthrough therapy status to Pfizer's RSV vaccine candidate

Shares of Pfizer Inc. PFE, +2.36% gained 0.6% in premarket trading on Wednesday after the company said its experimental respiratory syncytial virus (RSV) vaccine had received a breakthrough therapy designation from the Food and Drug Administration. The vaccine candidate is being evaluated in pregnant women to see if it can prevent illness among infants up to until the age of 6 months old. Several drug makers are developing RSV vaccines, including Moderna Inc. MRNA, -4.70% and GlaxoSmithKline GSK, +0.82%, though GSK this week halted a study assessing its investigational RSV shot in pregnant women, saying it needs to better understand the safety data. Pfizer's stock has gained 36.5% over the past year, while the broader S&P 500 SPX, +1.11% is up 10.3%.