Exploring the associations of weather and climate with HIV in sub-Saharan Africa: A systematic review

Background
UNAIDS has previously hypothesised that in sub-Saharan Africa, extreme weather/climate and HIV might be associated. A systematic review was conducted to summarise current evidence on the indirect associations between weather/climate variability and HIV-related measures (such as risk behaviours and access to care) in sub-Saharan Africa. This review does not assess environmental mediation of viral transmission.

Methods
Five literature databases (Web of Science, PubMed, SCOPUS and EMBASE, Global Health) were searched for relevant qualitative and quantitative studies that contained data on associations between weather/climate variables (including extreme weather events and changes in precipitation and temperature) and HIV measures (including HIV risk behaviours, and measures of HIV transmission and progression) in the general population of sub-Saharan Africa up to 6 April 2024. Results were summarised through narrative synthesis.

Results
Overall, 5853 non-duplicate papers were retrieved for abstract screening, with 57 studies selected for full-text screening. Of those, 20 studies (14 quantitative and six qualitative) were included in the review. Most studies suggested that weather/climate variability was associated with worsening of HIV-related outcome measures. Drought was the most frequently reported weather/climate exposure (12 studies in total), while HIV prevalence and antiretroviral therapy uptake were the most frequently reported HIV measures (10 and nine studies respectively). Few studies analysed data from longitudinal datasets and research gaps were identified on West and Central Africa, children, and key populations such as female sex workers.

Conclusions
Despite potential associations between weather/climate variability and HIV measures, primarily between droughts and HIV prevalence, there has been limited research published on the topic. The current evidence base is sparse, heterogenous, and insufficient to establish causality. The review highlighted the need for using longitudinal datasets to assess directionality and mediators of weather/climate-HIV relationships, while data on West and Central Africa, children, and key populations should be incorporated in future research.