A case-controlled study undertaken in patients of sexual health clinics in New Zealand showed that patients who received the outer membrane vesicle (OMV) meningococcal B vaccine (MeNZB) were 30% less likely to contract gonorrhea than patients who did not, making MeNZB the first vaccine to demonstrate protection against gonorrhea. Results from the study were published in The Lancet.1
Despite their different modes of infection and clinical presentation, meningococcal meningitis and gonorrhea are caused by pathogens that are close genetic relations. Neisseria gonorrhoeae and Neisseria meningitidis share an estimated 80% to 90% degree of homology in their primary DNA sequence.2 Ecological studies from Cuba, New Zealand, and Norway previously showed declines in new gonococcus infections immediately following vaccination campaigns using group B meningococcal OMV vaccines.
The study population consisted of patients age 15 to 30 years seen at New Zealand sexual health clinics who were born between January 1, 1984, and December 31, 1998 who were eligible to receive MeNZB during a mass immunization campaign that took placed from July 19, 2004 to June 30, 2006. The study included 11 clinics that provided records for 1241 incidences of gonorrhea, 12,487 incidences of chlamydia, and 1002 incidences of gonorrhea/chlamydia co-infection.
Using a unique ID number that is assigned to all New Zealand patients and used across health databases, the research team cross-referenced 3 data sources to link each patient’s MeNZB vaccination status to subsequent diagnoses of gonorrhea, chlamydia, or both. Data sources were the clinics’ records; the New Zealand National Health Index, which includes demographic information for any patient who has used the New Zealand health system; and the National Immunisation Register.
Following a multivariate analysis that adjusted for age group, ethnicity, sex, geographical location, and socioeconomic deprivation, vaccine effectiveness of MeNZB against confirmed cases of gonorrhea was estimated at 31% (95% CI, 21 to 39; P <.0001). “Modelling suggests that a vaccine with 30% efficacy could decrease the prevalence of gonorrh[o]ea by more than 30% within 15 years, if immunity is maintained,” wrote the investigators.
The researchers noted several potential limitations to the study, including the possibility that patients who received the vaccine might have been more willing to seek health care, and the possibility that confining the study population to patients at sexual health clinics may limit the applicability of the results to the general population.
Lead investigator Helen Petousis-Harris, PhD, from the department of general practice and primary health care at the University of Auckland in New Zealand told Infectious Disease Advisor that the findings of the study give clues as to what may be useful in a protective vaccine. “Unravelling both the features of the MeNZB vaccine that elicited the immunity and how that immunity was protective will be important steps in the future.”
MeNZB was developed in response to a specific meningococcal B outbreak and is no longer available. Dr Petousis-Harris suggested that currently available OMV vaccines Bexsero® and VA-MENGOC-BC® be evaluated against gonorrhea. “It may be that we already have a vaccine in our tool kit that can make a valuable contribution, even [if] it is not perfect.”
In an interview with Infectious Disease Advisor, sexually transmitted infections epidemiologist Nicola Low, MD, professor of epidemiology and public health at the University of Bern in Switzerland, noted that while technical problems have impeded the development of a gonorrhea vaccine, the fact that gonorrhea and other sexually transmitted infections do not attract public sympathy or attention presents another barrier. “Sexually transmitted infections are stigmatized and people who get gonorrhea are blamed for their infection and not thought deserving of help,” she stated. “The World Health Organization is developing an investment case for vaccines against sexually transmitted infections, including gonorrhea. This study should help to renew interest in a vaccine.”
Dr Petousis-Harris has been a consultant for GlaxoSmithKline, Merck, and Pfizer but has not received honoraria. Dr Black has been a consultant for Novartis Vaccines, and is currently a consultant for GlaxoSmithKline, Protein Sciences, Merck, and WHO. All other authors declare no competing interests. Funding for the study was provided by GSK Vaccines.
- Petousis-Harris H, Paynter J, Morgan J, et al. Effectiveness of a group B outer membrane vesicle meningococcal vaccine against gonorrhoea in New Zealand: a retrospective case-control study [published online July 7, 2017]. Lancet. doi:10.1016/S0140-6736(17)31449-31456.
- Tinsley CR, Nassif X. Analysis of the genetic differences between Neisseria meningitidis and Neisseria gonorrhoeae: two closely related bacteria expressing two different pathogenicities. Proc Natl Acad Sci U S A. 1996;93(20):11109-11114.