GlaxoSmithKline said its potential new blockbuster shot for respiratory syncytial virus appears to be more effective than rival Pfizer’s vaccine candidate, as the pair compete for a new market protecting older adults against the common lung infection.

In data released on Thursday, GSK said its vaccine showed overall efficacy of 82.6 per cent in a clinical trial, above Pfizer’s previously announced 66.7 per cent, although trials are not always directly comparable.

GSK’s vaccine candidate — which it plans to submit for approval this year — reduced severe RSV disease by 94.1 per cent, above Pfizer’s 85.7 per cent. The definitions of severe disease vary slightly between the trials.

Tony Wood, GSK’s chief scientific officer, said RSV remains one of the major infectious diseases without a vaccine, despite 60 years of research. The disease affects 64mn people and kills 160,000 a year.

“We believe that with the high vaccine efficacy demonstrated in this pivotal trial, our vaccine candidate has the potential to help reduce the significant global burden of RSV-associated disease in older adults, including those at the greatest risk of severe outcomes,” he said.

The company said it was safe and well tolerated, with mainly mild and transient side effects.

GSK and Pfizer are the frontrunners in a race for an RSV vaccine, with Johnson & Johnson, Bavarian Nordic and Moderna all developing their own candidates.

GSK’s vaccine only includes one strain of RSV, whereas Pfizer used two strains — but GSK said its vaccine candidate proved effective across both the A and B strains. GSK also used its adjuvant to boost efficacy, which Pfizer did not use.