The pipeline of new drugs to fight superbugs remains “worryingly thin” and has shrunk by 35% in the last five years, experts have warned, predicting the annual number of deaths linked to drug-resistant infections globally will double to 8 million by 2050.

The number of projects from large pharma companies has shrunk by 35% over the past five years, from 92 to 60 medicines in development, according to a report from the Access to Medicine Foundation (AMF), a Netherlands-based non-profit group, and the Wellcome Trust.

“Overall, however, the R&D pipeline remains worryingly thin, and industry investment has lost momentum,” said Jayasree K Iyer, the chief executive of AMF. She described drug resistance as the biggest single threat to healthcare worldwide.

More than 1 million people die each year directly from drug resistant infections but they contribute to 4 million deaths worldwide a year. Both figures are forecast to double by 2050 – to nearly 2 million and more than 8 million respectively.

The UK’s GSK is leading the way in antimicrobial resistance research and development (R&D) with 30 projects and is one of just three big pharma companies that continue to invest in this area, the report found.

The other two big players are Japan’s Shionogi and Otsuka, while the US drugmaker Pfizer, which was joint first with GSK in 2021, has fallen back.

Britain’s biggest pharmaceutical company, AstraZeneca, is not included in the ranking because it does not have an antibiotic portfolio, as infectious diseases has never been its focus. The report assesses the efforts of 25 companies, including seven large research-based firms, 10 generic medicine manufacturers and eight smaller drug developers, or biotechs.

Iyer said three recently approved antibiotics and seven other promising medicines in late-stage development showed “it is possible to tilt the battle against superbugs in humanity’s favour”.

In December, the US health regulator approved the Californian biotech Innoviva’s zoliflodacin (branded as Nuzolvence) to treat gonorrhea, as well as GSK’s gepotidacin (sold as Blujepa) for uncomplicated urinary tract infections and urogenital gonorrhea. They are the first antibiotics developed to treat these diseases in decades.

People in low- and middle-income countries, where infectious diseases hit hardest, are most vulnerable to drug-resistant superbugs. “There is no time to lose,” the AMF said.

Hospitals across the world have recorded an alarming rise in common infections that are resistant to antibiotics. One in six laboratory-confirmed bacterial infections were resistant to antibiotic treatments in 2023, with more than 40% of antibiotics losing potency against common blood, gut, urinary tract and sexually transmitted infections between 2018 and 2023, according to the World Health Organization.