Annual theme 2025: vaccine-preventable diseases in humans

Measles disproportionately affects under-vaccinated communities, and inequalities in vaccination coverage exist in the United Kingdom (UK). In Birmingham, England, 406 confirmed measles cases were notified to the UK Health Security Agency between 13 October 2023 and 12 April 2024. Public health case management system data and primary care vaccination data were used to describe the epidemiology of the outbreak. Cases had a median age of 5.5 years (interquartile range (IQR): 1–13); 53% (214/406) were male, 45% (183/406) female and sex was unknown for 2% (9/406). Most cases (89%; 362/406) were unvaccinated. While 78% (315/406) of cases occurred in the city’s most deprived areas (quintile 1), none did in the least deprived. The measles rate per 100,000 was 47.6 in quintile 1 vs 13.8 in quintile 3. Across ethnicities, the rate was 86.3 in Black African vs 10.8 in White British. Increases in vaccination rates between the outbreak period and an equivalent prior non-outbreak period seemed higher in most deprived populations (0.5% in quintile 1 vs 0.3% in quintiles 5). Variations, however, were observed between ethnic groups. In this large outbreak, measles disproportionately affected individuals from socioeconomically deprived backgrounds and ethnic minorities. In underserved communities, continued tailored services and vaccinations are required.

In November 2023, a cluster of two invasive meningococcal disease (IMD) cases caused by serogroup B Neisseria meningitidis (MenB) occurred in elderly residents (≥ 70 years) of a dementia care home in England. An epidemiological investigation was conducted and public health actions, including infection control measures and antibiotic chemoprophylaxis, were implemented to prevent further cases. Nasopharyngeal swabbing before chemoprophylaxis identified three meningococcal carriers, including two carrying the outbreak strain, highlighting the importance of immediate antibiotic prophylaxis in such settings. Microbiological investigations showed that the outbreak strain belonged to the sequence type (ST)-9316 complex, potentially covered by the 4CMenB vaccine. Although 4CMenB is licensed for children and adults, there are no safety or reactogenicity data on use in older adults (≥ 65 years). Given the severity of IMD, residents (64–95 years) and staff (18–72 years) were offered 4CMenB for longer-term protection, with daily diary cards to monitor side effects. In total, 30 residents and 35 of 47 staff received the first dose, with completed diary cards for 26 residents and 32 staff. Twenty-six residents and 28 staff received the second dose, and all completed diary cards. Elderly residents reported fewer and less severe side effects after each dose than younger staff.

During the 2024/25 influenza season, enhanced and standard-dose influenza vaccines were available for individuals aged 65 and older. Compared with the standard-dose quadrivalent influenza vaccine (QIV), the adjuvanted QIV was significantly more effective, with an overall vaccine effectiveness (VE) of 48% (95% CI: 42–52) vs 33% (95% CI: 24–41) when considering both non-hospitalised and hospitalised patients. The high-dose QIV demonstrated similar effectiveness to the adjuvanted QIV. These findings support the inclusion of enhanced influenza vaccines in future vaccination programmes.

We estimated early influenza vaccine effectiveness (VE) for the 2024/25 season in outpatients, in Beijing using a test-negative design. A(H1N1)pdm09 dominated (99.3%), all sequenced strains (n = 38) clustered in clade 6B.1A.5a.2a, and 37 of 38 antigenically similar to the vaccine strain. VE against any influenza virus infection was 48.5% (95% CI: 34.8–59.5) and 48.7% (95% CI: 35.1–59.7) against A(H1N1)pdm09. Vaccination in the current or previous season against any influenza showed a VE of 52.5% to 54.9%, compared to no vaccination in both seasons.

The 2024/25 influenza season in Europe is currently characterised by co-circulation of influenza A(H1N1)pdm09, A(H3N2) and B/Victoria viruses, with influenza A(H1N1)pdm09 predominating. Interim vaccine effectiveness (VE) estimates from eight European studies (17 countries) indicate an all-age influenza A VE of 32–53% in primary care and 33–56% in hospital settings, with some signals of lower VE by subtype and higher VE against influenza B (≥ 58% across settings). Where feasible, influenza vaccination should be encouraged and other prevention measures strengthened.

In 2024, circulating vaccine-derived poliovirus type 2 (cVDPV2) was detected in wastewater samples in Finland, Germany, Poland, Spain and the United Kingdom (UK). All strains were genetically linked, but sequence analysis showed high genetic diversity among the strains identified within individual wastewater sites and countries and an unexpected high genetic proximity among isolates from different countries. Taken together these results, with sequential samples having tested positive in various sites, a broader geographic distribution beyond positive sampling sites must be considered.