The UK has recently seen a resurgence of meningococcal B (MenB) disease, with a cluster of cases in Kent described as “unprecedented” by the health secretary, Wes Streeting. As attention turns from the current MenB outbreak to how to prevent future outbreaks, another challenge is also growing: gonorrhoea is becoming harder to treat as antibiotic resistance rises. These two challenges might seem unrelated, but they are now linked by a single vaccine.Some sexual health services are using a vaccine originally designed to prevent MenB disease as part of efforts to reduce gonorrhoea. At first glance, that might sound surprising. But the bacteria that cause meningitis and gonorrhoea are closely related, meaning a vaccine targeting one may offer some protection against the other.This kind of scientific overlap is drawing increasing attention. Developing brand new vaccines from scratch takes years – sometimes decades – and is costly. Repurposing existing ones could offer a faster, more practical route.The MenB vaccine itself already has a strong public profile in the UK. Campaigns calling for wider access became one of the most signed petitions in UK history. It has helped bring attention to meningococcal disease and shaping public expectations around vaccine availability. Recommendations about how vaccines are used in the UK are made by the Joint Committee on Vaccination and Immunisation, which operates within a government-defined framework. Their advice takes into account the burden of disease, vaccine safety and effectiveness, as well as the cost-effectiveness of different immunisation strategies.Repurposing vaccinesThe evidence is still evolving when it comes to gonorrhoea. While earlier studies suggested the MenB vaccine might offer some “cross-protection”, a more recent randomised control trial – the gold standard in medical research – indicates that protection may be lower in people who have previously had gonorrhoea.This raises important questions about who might benefit the most. If protection is stronger, or longer lasting, in people who have never had the infection, vaccination strategies may need to focus on these groups instead.Our recent research suggests that people are open to this kind of complexity. In a survey of sexual health service users in the UK, more than 98% supported the introduction of a gonorrhoea vaccine. Many were willing to accept that the vaccine might not be perfect, as long as its benefits were explained clearly and transparently. Ninety-eight per cent supported the introduction of a gonorrhoea vaccine. Stephen Barnes/Shutterstock.com That willingness matters. Repurposed vaccines are unlikely to offer complete protection, especially in the early stages. But even partial protection could reduce cases and ease pressure on healthcare systems, particularly for infections like gonorrhoea, where treatment options are narrowing.At the same time, the context in which this vaccine is being used is changing. The UK is seeing renewed concern about MenB disease, including clusters of cases that have spread quickly. This places the MenB vaccine in an unusual position: it is being deployed simultaneously against a rare but severe infection and a common, increasingly drug-resistant one.These overlapping pressures may shift how we think about its value. Traditionally, decisions about a national MenB programme have been based on the burden of meningococcal disease alone. But if the same vaccine can also contribute – even partially – to controlling gonorrhoea, the calculation becomes more complex.In that light, the question is no longer just whether the MenB vaccine is cost-effective for one disease, but whether its combined impact across multiple infections changes the equation altogether.There are also practical considerations. Vaccine supply, delivery capacity and prioritisation all come into play when a single product is expected to address more than one public health challenge. Expanding its use would require careful planning to avoid displacing more effective or cost-effective interventions. Not just single-purpose toolsAt the same time, this approach highlights a broader shift in biomedical thinking. Vaccines are increasingly being understood not just as single-purpose tools, but as tools that may have wider effects than originally anticipated. As our understanding of pathogens and immune responses deepens, opportunities to reuse or adapt existing drugs and vaccines are likely to grow.With rising levels of antibiotic-resistant gonorrhoea alongside renewed concern about MenB, and strong public support for vaccination, the case for wider use of this vaccine may look different to before. Whether that ultimately leads to routine immunisation will depend on the evolving evidence. But this moment may mark the beginning of a broader shift in how we evaluate vaccines, not just in terms of single diseases, but in terms of their potential to address multiple threats at once.Charlie Firth receives funding from the National Institute for Health Research