ABSTRACT Climate change disproportionately affects vulnerable populations, including those of lower socioeconomic status, people living with HIV, and young children living in low-resource settings. Malawi has seen a massive increase in extreme weather events related to climate change in recent years, culminating in Cyclone Freddy, believed to be the longest-lasting and highest force cyclone ever recorded, which hit Malawi on March 11th. Independent of direct morbidity or mortality due to drowning or blunt injury, Cyclone Freddy may have severely impacted the health of Malawian children through exposure to a broad range of infectious diseases, and increased experiences of psychosocial adversities resulting in prolonged periods of toxic stress. We are currently following a cohort of mothers (recruited in the third trimester of pregnancy) and infants being followed up to five years of age in three categories: (1) children HIV exposed and uninfected (CHEU) born to women diagnosed with HIV at the first antenatal visit, thus exposed to uncontrolled viremia for at least half of gestation; (2) CHEU born to women initiated on ART prior to conception with undetectable viral loads; and (3) infants born to HIV uninfected mothers. Our goal is to conduct rigorously validated longitudinal assessments of neurocognitive development and biological and psychosocial factors which may play a role in child development. We are leading one of the first studies of CHEU in resource-limited settings to simultaneously address the impact of biological and psychosocial factors on neurocognitive development. In this supplement, we are planning to incorporate climate change information into our assessment of the impact of maternal HIV infection and the post-natal environment on long-term health and neurocognitive outcomes in children. Our evaluation will include assessing the impact of Cyclone Freddy and other extreme weather events on neurocognitive development in HIV-exposed infants by evaluating the impact of these factors on the family’s quality of life as reported by the mother and exposure to vector-borne infections. We will test the following hypotheses: 1a: Cyclone Freddie will lead to increased rates of maternal depression, increased severity of exposure to childhood adversity, and decreased quality of housing. The impact will be greatest among mothers living with HIV. 1b: the neurocognitive development of infants in households that report significant impacts of the cyclone is likely to be delayed compared to households which do not report major impacts. 2a: Extreme weather events will lead to an increase in arboviral exposure, this effect will be greatest among households with lower SES, CHEU, and mothers living with HIV. 2b: Exposure to arboviruses will be associated with poorer neurocognitive scores at five years of age, particularly among CHEU. This research will measure the impact of these climate-related factors on the health and well-being of HIV- exposed compar...