Evaluating the impact of COVID-19 on the HIV epidemic among men who have sex with men in Australia

Government-imposed physical distancing restrictions during the COVID-19 pandemic disrupted biobehavioral HIV prevention practices and access to healthcare services. This study aimed to use a mathematical model to evaluate the impact of COVID-19 on the HIV epidemic among men who have sex with men in Australia, using empirical data. A retrospective modeling study. We developed a mathematical model to estimate monthly HIV incidence between January 2020 and August 2022. We obtained aggregated monthly data for sexual partners, condom use, HIV testing, pre-exposure prophylaxis (PrEP) use, and migration. Three scenarios were simulated: 1) a COVID-19 scenario; 2) a no COVID-19 scenario where input parameters remained at pre-COVID-19 values; and 3) a no COVID-19 scenario with continued PrEP scale-up. In the absence of the COVID-19 pandemic, 1,263 (95% Percentile Interval (PI): 880-1,706) infections would have occurred between January 2020 and August 2022 compared to 915 (95% PI: 638-1,282) for the COVID-19 scenario (a 27.6% reduction). Reduced sexual partners was the leading factor contributing to the change in HIV infections and diagnoses (-24.9% and -10.6%, respectively). MSM aged ≥50 years had a larger reduction (31.0%) in new HIV infections than their younger counterparts (19.9%). A substantial reduction in new HIV infections and diagnoses in Australia occurred during the COVID-19 pandemic, largely due to decreased numbers of sexual partners. This reduction underscores the need for sustained public health strategies leveraging reduced transmission rates to continue progress towards eliminating HIV in Australia.