Leveraging remnant viral load samples for SARS-CoV-2 antibody seroprevalence trends among PLHIV in Kenya, February 2021-October 2022: a cross-sectional surveillance survey.

INTRODUCTION: People living with HIV (PLHIV) are at increased risk of COVID-19-related mortality. However, the burden of and immune response to SARS-CoV-2 infection among PLHIV, particularly in sub-Saharan Africa, remains poorly understood. METHODS: We conducted a four-round serial cross-sectional surveillance survey using HIV viral load testing remnant samples from PLHIV on antiretroviral treatment (ART) in Kenya to assess trends in SARS-CoV-2 antibody seroprevalence from February 2021 to October 2022. SARS-CoV-2 IgG antibodies were detected using a validated two-assay ELISA serial algorithm. Samples with ELISA-positive or borderline result samples were further tested using a multiplex bead assay (MBA) to distinguish potential infection and/or vaccination status. RESULTS: National SARS-CoV-2 antibody seroprevalence among PLHIV on ART increased from 16.1% in round 1 to 91.7% in round 4: round 1: 16.1% (95% CI 6.9% to 33.1%), round 2: 29.6% (95% CI 13.7% to 52.7%), round 3: 84.2% (95% CI 67.7% to 93.1%) and round 4: 91.7% (95% CI 86.5% to 95.0%). These estimates corresponded to approximately 186 891 (95% CI 38 639 to 3 35 143), 363 590 (95% CI 114 267 to 612 913), 1 072 496 (95% CI 914 449 to 1 230 452) and 1 173 399 (95% CI 1 120 224 to 1 226 574) PLHIV on ART with SARS-CoV-2 antibodies across the four rounds. MBA testing of ELISA-positive and borderline samples showed that 97% had evidence of probable infection and/or vaccination while 3% tested negative by MBA. CONCLUSIONS: Monitoring SARS-CoV-2 infection in PLHIV is essential. Seroprevalence among PLHIV on ART in Kenya increased substantially during 2021-2022, reflecting both infection and vaccination. Protecting the health of PLHIV through sustained prevention, treatment and vaccination strategies remains critical in mitigating the threat of COVID-19.