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Background Oral human papillomavirus (HPV) infections are a leading cause of oropharyngeal cancers. In 2015 and 2016, HPV vaccines became publicly funded for gay, bisexual, and other men who have sex with men (GBM) under 27 years of age in most Canadian provinces. Methods Between 2017 and 2019, sexually active GBM in Montreal, Toronto, and Vancouver were recruited through respondent-driven sampling. Participants aged 16–30 years were invited to self-collect oral rinse specimens for HPV testing. We estimated HPV prevalence in the oral tract overall and compared these by vaccination status. Results Among the 838 GBM with a valid oral specimen, 36.9% reported receiving ≥1 dose of HPV vaccine. Overall, oral HPV prevalence was 2.6% (95% confidence interval [CI], 1.5%–3.7%) for at least 1 HPV type and 1.2% (95% CI,.5%–1.9%) for any high-risk type. We detected quadrivalent (HPV 6/11/16/18) vaccine-preventable types in 0.3% (95% CI,.0%–1.0%) of vaccinated individuals and 1.1% (95% CI,.1%–2.0%) of unvaccinated individuals. Conclusions Oral HPV prevalence was low in a population of young urban GBM in Canada, of whom 37% were vaccinated. Findings serve as a benchmark for monitoring of vaccination impacts on oral HPV infection within this priority population. [ABSTRACT FROM AUTHOR]

We estimated the effectiveness of booster doses of monovalent and bivalent mRNA COVID-19 vaccines against Omicron-associated severe outcomes among adults aged ≥50 years in Ontario, Canada. Monovalent and bivalent mRNA COVID-19 booster doses provided similar strong initial protection against severe outcomes. Uncertainty remains around waning of protection from these vaccines. [ABSTRACT FROM AUTHOR]

Background Real-world evidence of human papillomavirus (HPV) vaccine effectiveness (VE) against longitudinal outcomes is lacking among gay, bisexual, and other men who have sex with men (GBM). We compared 12-month incidence and persistence of anal HPV infection between vaccinated and unvaccinated GBM. Methods We recruited GBM aged 16–30 years in Montreal, Toronto, and Vancouver, Canada, from 2017 to 2019. Participants were followed over a median of 12 months (interquartile range, 12–13 months). Participants self-reported HPV vaccination and self-collected anal specimens for HPV DNA testing. We calculated prevalence ratios (PR) for 12-month cumulative incidence and persistence with ≥1 quadrivalent vaccine type (HPV 6/11/16/18) between vaccinated (≥1 dose at baseline) and unvaccinated participants using a propensity score-weighted, modified Poisson regression. Results Among 248 participants, 109 (44.0%) were vaccinated at baseline, of whom 62.6% received 3 doses. PRs for HPV 6/11/16/18 were 0.56 (95% confidence interval [CI],.24–1.31) for cumulative incidence and 0.53 (95% CI,.25–1.14) for persistence. PRs were 0.23 (95% CI,.05–1.03) and 0.08 (95% CI,.01–.59) for incidence and persistence, respectively, among participants who received their first dose at age ≤23 years and 0.15 (95% CI,.03–.68) and 0.12 (95% CI,.03–.54) among participants who were sexually active for ≤5 years before vaccination. Conclusions Findings support national recommendations for HPV vaccination at younger ages or soon after sexual debut. [ABSTRACT FROM AUTHOR]

We estimated the effectiveness of a fourth dose of mRNA COVID-19 vaccine against Omicron infections and severe outcomes over time among long-term care residents in Ontario, Canada. Fourth doses provide additional protection against Omicron-related outcomes, but the protection wanes over time, with more waning seen against infection than severe outcomes. [ABSTRACT FROM AUTHOR]