Efficacy Trial on Meningococcal B Vaccine for Preventing Gonorrhea Infections

Efficacy of a Meningococcal B Vaccine Against Neisseria Gonorrhoeae Infections Among Men Who Have Sex With Men: a Randomised-controlled Clinical Trial

Objectives: Efficacy of a meningococcal vaccine against Neisseria gonorrhoea (NG) infection among men who have sex with men (MSM). Design: Parallel randomised double-blind placebo-controlled trial. Setting: A teaching hospital in Hong Kong. Participants: 150 adult MSM at risk of gonorrhoea infection (condomless sex with more than one man within the last six months, history of sexually transmitted infection [STI] diagnosis, inclination to have condomless sex, and other PrEP-eligible criteria) would be recruited into the trial, with half allocated to intervention and control group each. Intervention: Intervention and control group would receive, one month apart, two doses of meningococcal vaccine and normal saline, respectively. Main outcome measures: Safety and efficacy of vaccine against gonorrhoea (time to first gonorrhoea infection and incidence), and behavioural change after vaccination. Expected results: NG incidences in two groups would be compared. Efficacy of vaccine against gonorrhoea would be determined after controlling confounding variables. Characteristics of participants with incident NG would be distinguished from those without incident infections. Change of frequency of sexual activities and networking would be noted. Implications: Strategies on STI screening and vaccination could be informed. Reduced STI burden post-vaccination could be measured with surveillance system.

Participants in the vaccination group would receive two doses of 4CMenB vaccine 1 month apart (at Month 0 and Month 1) while subjects in the control group would receive two doses of normal saline of a similar volume.

Block randomisation would be used to generate the list of treatment groups with a block size of 4 in a centralised computer by a staff in the Research Centre unrelated to data analysis. Group assignment would be concealed and performed by another staff unrelated to data analysis who will pick the group number from the random allocation sequence in sequential order. The subjects and investigators would therefore be blinded.

Inclusion Criteria: Male adult who has had sex with another male in the past six months Ages 18 years or above Normally resides in Hong Kong Able to communicate in written and spoken Chinese or English At risk of gonorrhoea infection (had condomless sex with more than one man within the last six months, history of STI diagnosis, inclination to have condomless sex, and other PrEP-eligible criteria) Negative NG test result at the time of recruitment No history of previous vaccination with MenB vaccines Able and willing to attend all study visits Exclusion Criteria: Contraindications to receive MenB vaccine Unable to give informed consent