Evaluation of a rapid test against two ELISAs for a SARS-CoV-2 seroprevalence survey in Kibera informal settlement, Nairobi, Kenya

Introduction The performance of a rapid test was evaluated against two ELISAs as a potentially useful tool to determine exposure to SARS-CoV-2 in low resource settings. A serosurvey was conducted in Kibera informal settlement, Nairobi, Kenya, where low numbers of COVID-19 were recorded during the pandemic. Materials and methods A cross-sectional study was performed in 10 of 14 villages in Kibera informal settlement, Kenya’s largest slum community, in August 2021, before general vaccine roll-out. Participants were age one year and above with no symptoms of COVID-19. Capillary blood samples were tested using the Standard Q COVID-19 IgM/IgG Combo rapid test, Platelia SARS-CoV-2 Total Ab (IgM/IgG/IgA) Assay, and Wantai Total Ab (IgM/IgG/IgA) ELISA for SARS-CoV-2 which served as the reference test. Results Samples were obtained from 438 participants; in 72 samples blood was insufficient for the Platelia ELISA. Specificity of the rapid test and Platelia ELISA were similar (>93%) but sensitivity was low (rapid test 61.3%; Platelia ELISA 83.4%). The Wantai ELISA showed greater positivity (82.6%) than the rapid test (51.8%) and Platelia ELISA (69.7%). Conclusions The Wantai ELISA showed superior performance in this serosurvey. Point-of-care tests for convenient screening for SARS-CoV-2 exposure for surveillance studies need to be developed.