Five doses under the tongue prompted immune responses in mice to a bacterium that causes more than 600 million infections worldwide each year. The early study, led by the United Kingdom’s Medicines and Healthcare products Regulatory Agency (MHRA) with the GSK Vaccines Institute for Global Health, points to a possible needle-free route for a future Strep A vaccine.
Group A streptococcus, commonly called Strep A, can cause infections ranging from mild sore throats to severe illness. Serious complications can lead to lasting disability or death. The disease burden is especially high in low- and middle-income countries, and complications linked to Strep A are estimated to cause more than 500,000 deaths annually. No vaccine against Strep A is currently licensed.
In the experiment, researchers gave one group of eight mice a vaccine candidate under the tongue once a week for five weeks. A comparison group of five mice received a saline solution, known as PBS. The candidate combines a Strep A carbohydrate with generalized modules for membrane antigens, or GMMA. These are tiny bubbles naturally released by bacteria. In the vaccine, they carry the carbohydrate and also act as an adjuvant, a substance that helps strengthen the body’s immune response.
The route matters because Strep A first meets the body at moist surfaces in the nose and throat. Many vaccines mainly aim to produce antibodies circulating in the blood. This approach was designed to prompt responses at those entry points as well as a wider immune response throughout the body. The study reported responses in both places after vaccination in the mice.
The findings, published in October 2026 in Human Vaccines & Immunotherapeutics, add to research into vaccines delivered without a needle, including through the nose or under the tongue. Such methods could be easier to give and could help widen access, particularly in places where the disease causes the greatest harm. If future studies show that the approach can prevent illness, vaccination could also reduce the need for antibiotics and support efforts to slow antimicrobial resistance, when germs become harder to treat with medicines.
For now, the results are a starting point, not evidence that the candidate protects people. The work was done in mice as part of the MHRA’s broader research into vaccines, immune responses, testing methods and new ways to deliver vaccines. More research will be needed before scientists know whether the approach is safe and effective in people. The team’s results suggest that reaching the nose and throat as well as the bloodstream may be a useful direction as researchers work toward a Strep A vaccine that is both accessible and practical to administer.