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GSK sets high bar with trial results for RSV vaccine

Dive Brief:

  • GSK’s vaccine for respiratory syncytial virus proved strongly effective in a large Phase 3 trial, reducing cases of lower respiratory infection in people 60 years and older by 83% when compared to those given a placebo. The U.K. drugmaker gave the results from its trial on Thursday, ahead of an infectious diseases conference next week.


  • The shot is the first of its type to have full data from a trial designed to support regulatory approval, with candidates from Pfizer and Johnson & Johnson expected to follow later this year. Pfizer previously released interim data from its trial, indicating the shot was 67% effective against lower-respiratory tract infections, but the company hasn’t disclosed a full analysis.


  • After decades of failure, vaccine researchers in recent years figured out how to direct the body’s immune system against a protein specific to RSV, prompting a race to develop the first preventive shot against a virus that causes hundreds of thousands of hospitalizations and tens of thousands of deaths. Moderna, Sanofi and Bavarian Nordic are also testing RSV vaccines.

Dive Insight:

The new GSK data should set a bar for rivals developing an RSV vaccine for older people. The shot was effective in analyses of patients by severity, age group and health problems, and had only mild side effects that are common to other types of vaccines, GSK reported.

Against more severe cases — defined by patients having two or more lower respiratory signs or symptoms of disease — the efficacy observed was even higher at 94%. By comparison, Pfizer’s interim analysis showed its shot was 86% effective against severe disease, as defined by three or more lower-respiratory tract symptoms.

Measured by age, GSK’s shot outperformed placebo in all groups but those study participants aged 80 and over. In that cohort, only two patients receiving the shot and three given a placebo became sick with an RSV infection — a difference that wasn’t statistically significant.

Among patients defined as “frail,” meaning they walked very slowly or were unable to walk, only one patient each in the active vaccine group and placebo arm became sick.

Patients with other health problems analyzed by GSK, including cardiovascular and metabolic disease, benefited from receiving the shot. It was also broadly effective against both the A and B subtypes of the virus.

GSK plans to ask the Food and Drug Administration and other regulators to approve its vaccine by the end of 2022. Pfizer has said it will do the same in the coming months, along with J&J. Vaccine trials in pregnant women and babies are also underway.

Sanofi and AstraZeneca, meanwhile, recently gained the backing of a European Medicines Agency advisory committee for an antibody drug called Beyfortus to prevent RSV infections in newborns and babies.