© SPL. Neisseria gonorrhoeae, SEM.

Further support for cross protection of meningococcal B vaccine against gonorrhoea

By Rebecca Jenkins
An existing meningococcal B (MenB) vaccine offers cross protection against gonorrhoea, according to Australian research, which could herald a new way to combat rising cases of the sexually transmitted infection (STI).

More than 80 million new cases of gonorrhoea were recorded worldwide in 2020, but with no licensed gonorrhoea-specific vaccine and reports of drug resistance, experts are concerned the STI will become harder to treat in the future, or perhaps untreatable.

Building on previous studies from New Zealand and Canada suggesting the MenB vaccine offered moderate protection against gonorrhoea, researchers in Adelaide conducted a cohort and case-control observational study to assess cross protection from the ongoing South Australia four component serogroup B meningococcal (4CMenB) vaccination program.

Australian Immunisation Register data recorded more than 53,000 adolescents and young adults receiving at least one dose of 4CMenB vaccine during the program’s first two years, researchers reported inThe Lancet Infectious Diseases, with state disease notification data showing the vaccine was highly protective against meningitis B and sepsis.

Using age-matched individuals with chlamydia as controls, researchers were also able to show two doses of the vaccine in adolescents and young adults were 33% effective against gonorrhoea.

The study was published alongside a US observational study of health records for 16- to 23-year-olds in New York City and Philadelphia during 2016 to 2018 that indicated two doses of 4CMenB provided 40% protection against gonorrhoea.

Lead author of the Australian study, Professor Helen Marshall AM, Professor of Vaccinology at the University of Adelaide, and Consultant in Vaccinology at Adelaide’s Women’s and Children’s Hospital, said both studies built on other research suggestive of a moderate protective effect of 4CMenB vaccine against gonorrhoea.

‘There are a number of modelling studies that now show even a moderate effect as identified in these multiple studies will significantly reduce gonorrhoea infections and their complications,’ she told Medicine Today.

‘The evidence for use of the 4CMenB vaccine to protect young people against two diseases that significantly affect their health is mounting and although the 4CMenB vaccine is currently only indicated for meningococcal B prevention, it would be great to see some consideration to providing the vaccine through funded programs to young people to potentially protect them against two diseases with one vaccine.’

Meningococcus and gonococcus were from the same Neisseria bacterial genus, Professor Marshall said, and shared 90% of their genes.

‘The 4CMenB vaccine contains the protein NHBA [neisserial heparin binding antigen] which is exposed on the surface of the gonococcus and recognised by antibodies from people vaccinated with 4CMenB vaccine. Vaccinated individuals develop cross-reactive antibodies to other proteins in the vaccine’s outer membrane vesicle as well as the NHBA protein, and these antibodies are effective against the gonococcus,’ she said.

Further research was needed to track how long the protection against gonorrhoea lasted, Professor Marshall added, noting her research group would soon have data on three years post introduction of the 4CMenB vaccination program.

‘It would be ideal to measure the effectiveness of 4CMenB vaccine against gonorrhoea in a randomised controlled trial and there are two studies that have started recruitment of high-risk individuals to measure the impact using this gold-standard design,’ she said.
Lancet Infect Dis 2022; doi: https://doi.org/10.1016/S1473- 3099(21)00754-4.
Lancet Infect Dis 2022; doi: https://doi.org/10.1016/ S1473-3099(21)00812-4.