London, May 18, 2026, 15:11 (BST)
- GSK shares were up 0.93% at 1,879.81p, while the FTSE 100 rose about 1.0%. Investing
- Japan expanded approval of GSK’s RSV vaccine Arexvy to at-risk adults aged 18 to 49. Investegate
- GSK also disclosed 1.67 million share purchases under its buyback programme. Investegate
GSK shares rose in London on Monday after Japan expanded approval for Arexvy, the British drugmaker’s respiratory syncytial virus vaccine, giving investors a fresh regulatory win in vaccines while the company continued to buy back stock.
The shares were recently at 1,879.81 pence, up 0.93%, after opening at 1,855.50p and touching 1,880.42p, according to market data. The FTSE 100, London’s blue-chip index, was also higher at 10,296.36, up 0.99%. Investing
The approval matters because GSK is trying to broaden Arexvy’s use after a volatile period for vaccine sales. In first-quarter results last month, GSK reported total sales of £7.6 billion, up 5% at constant exchange rates, but Arexvy sales of £0.1 billion were down 18%.
GSK said Japan’s Ministry of Health, Labour and Welfare expanded Arexvy’s eligible population to adults aged 18 to 49 who are at increased risk of RSV disease. RSV, or respiratory syncytial virus, is a common respiratory virus that can lead to severe illness in older adults and people with some chronic conditions. Investegate
Sanjay Gurunathan, GSK’s head of vaccines and infectious diseases research and development, said the expanded approval “can help reduce potentially severe outcomes of RSV.” The company said Arexvy had already been approved in Japan for all adults aged 60 and older and for at-risk adults aged 50 to 59. Investegate
The decision was backed by trial data showing a non-inferior immune response in at-risk adults aged 18 to 49 compared with adults aged 60 and above. Non-inferior means the response was not meaningfully worse than the comparator group. GSK said the safety profile was consistent with earlier trials. Investegate
Arexvy sits in a crowded RSV field. Reuters reported in March, after a U.S. label expansion, that GSK’s shot would compete in the high-risk 18-49 adult group with Moderna’s mRESVIA and Pfizer’s Abrysvo, two rival RSV vaccines. Reuters
Separately, GSK said on Monday it had bought 1,671,851 ordinary shares between May 11 and May 15 through Citigroup. The purchases were made at volume-weighted average prices ranging from 1,855.48p to 1,882.24p, and the shares will be held as treasury shares, meaning bought-back shares kept by the company rather than cancelled immediately. Investegate
The purchases form part of the fifth and final tranche of GSK’s £2 billion buyback programme. A buyback is when a company repurchases its own shares, often reducing the share count and lifting earnings per share if profits hold steady. GSK has said the final tranche is worth up to about £0.18 billion and is expected to finish by June 26. Investegate
The broader investor case remains tied to execution. GSK reaffirmed 2026 guidance last month for turnover growth of 3% to 5% and core earnings per share growth of 7% to 9% at constant exchange rates, which strip out currency moves. Chief Executive Luke Miels said GSK had made “a strong start to 2026.”
But the risk is that a wider label does not quickly become sales. Pricing, reimbursement and vaccination policy in Japan could shape uptake, while Pfizer and Moderna remain active competitors in RSV. GSK’s own 2026 outlook calls for vaccine sales to be down by a low single-digit percentage to stable, so the near-term revenue lift from Japan may be limited.
