Single-dose Effectiveness of Mpox Vaccine in Quebec, Canada: Test-negative Design With and Without Adjustment for Self-reported Exposure Risk.

INTRODUCTION: During the 2022 mpox outbreak, the province of Quebec, Canada, prioritized first doses for pre-exposure vaccination of people at high mpox risk, delaying second doses due to limited supply. We estimated single-dose mpox vaccine effectiveness (VE) adjusting for virus exposure risk based only on surrogate indicators available within administrative databases (eg, clinical record of sexually transmitted infections) or supplemented by self-reported risk factor information (eg, sexual contacts). METHODS: We conducted a test-negative case-control study between 19 June and 24 September 2022. Information from administrative databases was supplemented by questionnaire collection of self-reported risk factors specific to the 3-week period before testing. Two study populations were assessed: all within the administrative databases (All-Admin) and the subset completing the questionnaire (Sub-Quest). Logistic regression models adjusted for age, calendar-time and exposure-risk, the latter based on administrative indicators only (All-Admin and Sub-Quest) or with questionnaire supplementation (Sub-Quest). RESULTS: There were 532 All-Admin participants, of which 199 (37%) belonged to Sub-Quest. With exposure-risk adjustment based only on administrative indicators, single-dose VE estimates were similar among All-Admin and Sub-Quest populations at 35% (95% confidence interval [CI]:-2 to 59) and 30% (95% CI:-38 to 64), respectively. With adjustment supplemented by questionnaire information, the Sub-Quest VE estimate increased to 65% (95% CI:1-87), with overlapping confidence intervals. CONCLUSIONS: Using only administrative data, we estimate one vaccine dose reduced the mpox risk by about one-third; whereas, additionally adjusting for self-reported risk factor information revealed greater vaccine benefit, with one dose instead estimated to reduce the mpox risk by about two-thirds. Inadequate exposure-risk adjustment may substantially under-estimate mpox VE.

Factors Shaping Gay Men's Experience of Intimate Partner Violence: An Ecological View.

Gay men are particularly at risk for intimate partner violence (IPV). As regards the prevalence and unique consequences of IPV, many studies seek to understand the specific stressors faced by gay men, but few provide a more comprehensive perspective of IPV-related factors, including gay men-specific, general as well as protective factors. An ecological perspective was used to conduct a qualitative study aimed at identifying the different risk and protective factors related to IPV among gay men. We conducted individual semi-structured interviews with 23 gay men who acknowledge having experienced IPV by another man, as well as two focus groups with practitioners who provide services to this population. Our analysis led to a five-level ecological model, ranging from most proximal (e.g. prior victimization) to distal (e.g. conception of masculinity) factors, and including both general factors (e.g. power dynamics) and factors specific to gay men. Heterosexism emerged as an overarching contributing sociocultural factor. This study sheds new light on mechanisms whereby these factors affect the IPV experience, namely the risk of being victimized; the recognition of IPV victimization; and the response to the IPV experienced. These mechanisms are discussed along with heterosexism-related factors, and implications for research and practices are suggested.