Table 1.

Summary of vaccine-targeting strategies considered

	Eligibility	Number of people eligible per year	Average risk of eligible people	Explanation
Vaccination before entry (VbE)	Adolescents before they become sexually active, with only those in the relevant age-cohort each year being eligible; vaccination would be offered to all adolescents, irrespective of sexual orientation, and would be done to protect against meningitis or gonorrhoea, or both	Small, remaining constant	Same as the population	No targeting by future risk; this strategy with a vaccine that is protective against gonorrhoea would have some beneficial effect on gonorrhoea in MSM (analysed in this study) as well as some beneficial effect on gonorrhoea in other population groups (outside the scope of our analysis)
Vaccination on diagnosis (VoD)	MSM diagnosed with gonorrhoea in sexual health clinics, both through seeking care for symptomatic infection and through attending for screening (testing in the absence of symptoms)	Small, declining slightly as cases are averted	Much higher than the population average	Individuals with higher-risk behaviour are more likely to become infected and to then have the infection diagnosed, either due to symptomatic care-seeking or through screening
Vaccination according to risk (VaR)	MSM diagnosed with gonorrhoea in sexual health clinics, plus those MSM attending sexual health clinics for screening who report high-risk sexual behaviour	Moderate, declining to a small number as cases are averted	Highest of all	Includes all individuals eligible under VoD, plus those with high-risk behaviour who are not infected at the time of attendance
Vaccination on attendance (VoA)	MSM attending sexual health clinics, both those seeking care for symptomatic infection and those attending for screening, with vaccination offered irrespective of gonorrhoea infection status	Large, declining to a moderate number as cases are averted	Higher than the population average	Individuals with higher-risk behaviour are more likely to attend clinics for screening than lower-risk individuals, and are more likely to become infected and attend clinics to seek care for symptomatic infection

MSM=men who have sex with men.