evidence: We used the following sociodemographic characteristics in our analyses: age group, ethnicity, gender, sexual orientation, country of birth, nation of residence in the United Kingdom (England, Scotland, Wales, or Northern Ireland), education level, employment, household composition (living alone or not), relationship status (single or in a relationship), and report of a comfortable financial situation from the top 2 quartiles (e.g., a response of "I am comfortable" or "I am very comfortable" from the question "How would you best describe your current financial situation?"). We also used clinical characteristics in our multivariable analyses, including HIV status and uptake of >1 vaccine doses for hepatitis A virus (HAV), hepatitis B virus (HBV), or human papillomavirus (HPV). We defined behavioral risk modification as the report of any of the following beginning in May 2022: fewer sexual partners; reduced visits to sex on premises venues or PSE; or avoiding any sex, condomless anal sex, skin-to-skin contact, or visiting clubs or crowds. [...] Additional members of the UK Health Security Agency Sexual Health Liaison Group who contributed to the review and update of the survey instrument, analysis plan, and interpretation of findings: Katy Sinka, Helen Fifer, Hannah Charles, Helen Corkin, Norah O’Brien, and Kate Folkard.