Reported frequency of condomless anal or vaginal sex by sociodemographic group and calendar year with a partners of any HIV status and b partners of HIV negative/unknown status, HIV Outpatient Study, USA, 2007–2019 (N = 2193). a Linear regressions of the frequency of condomless sex by MSM during 2008–2011 and 2011–2019 were the following: 0.83 (95% CI 0.74–0.93, P = 0.001), and 1.53 (95% CI 1.26–1.86, P < 0.001), respectively. Similar linear regression results for heterosexual males and all females were not statistically significant. Het heterosexual; MSM men who have sex with men. b Linear regressions of the frequency of condomless sex with partners of negative or unknown HIV status by MSM during 2008–2011 and 2011–2019 were the following: 0.77 (95% CI 0.69–0.87, P < 0.001), and 1.65 (95% CI 1.34–2.13, P < 0.001), respectively. Similar linear regression results for heterosexual males and all females were not statistically significant