Estimated HIV cases and costs in South Africa due to global warming from 2000 to 2050: a modeling study

The impact of global warming on HIV prevalence and costs in South Africa are not known. We estimated for 2000-2020 using recorded surface temperatures and for 2021-2050 using predicted temperatures from the MAGICC7.0 climate model. In the latter case we assumed that societal development and temperatures would follow the narrative of Shared Socioeconomic Pathway (SSP) 2. We considered as a best-case, pathway 1 (SSP1). To estimate the number of people whose infection status can be associated with rising temperatures (PLHIV-T), we estimated temperature-related prevalence risks, which we applied to predicted prevalence from the Thembisa HIV transmission model. We derived incidence from prevalence using previously established methods. For the former, we also estimated follow-up antiretroviral therapy (ART) costs. PLHIV-T has increased by 7-fold from 2001 to 2020, from 1,712 to 13,254. ART costs for PLHIV-T have correspondingly increased from US$2.07 million in 2010 to US$2.89 million in 2015 and then declined to US$2.02 million in 2020. If societal development remained unchanged from 2020 to 2050, PLHIV-T associated with temperatures predicted by SSP2 increases by nearly 1.5-fold by 2050, to 14,033 (0.2% of all prevalent cases; incidence at a rate of 1.44 per 100-person-years) with US$2.25 million in ART costs. Alternatively, if societal development followed SSP1, then in 2050, the penalty would be nearly the same with 14,009 instead of 14,033 PLHIV-T and US$ 2.25 million in ART costs. Societal development alone does not sufficiently mitigate climate related health losses. Stakeholders must therefore prioritize health adaptation within climate financing and integrate HIV response planning into national climate resilience strategies.