High seroprevalence of Immunoglobulin G (IgG) and IgM antibodies to SARS-CoV-2 in asymptomatic and symptomatic individuals amidst vaccination roll-out in western Kenya

Abstract

AbstractBackgroundThe population’s antibody response is a key factor in comprehending SARS-CoV-2 epidemiology. This is especially important in African settings where COVID-19 impact, and vaccination rates are relatively low. This study aimed at characterizing the Immunoglobulin G (IgG) and Immunoglobulin M (IgM) in both SARS-CoV-2 asymptomatic and symptomatic individuals in Kisumu and Siaya counties in Western Kenya using enzyme linked immunosorbent assays.ResultsThe IgG and IgM overall seroprevalence in 98 symptomatic and asymptomatic individuals in western Kenya between December 2021-March 2022 was 76.5% (95% CI =66.9-84.5) and 31.6% (95% CI =22.6-41.8) respectively. In terms of gender, males had slightly higher IgG positivity 87.8% (36/41) than females 68.4% (39/57). Amidst the ongoing vaccination roll-out during the study period, over half of the study participants (55.1%, 95% CI= 44.7-65.2) had not received any vaccine. About one third, (30.6%, 95% CI= 21.7-40.7) of the study participants had been fully vaccinated, with close to a quarter (14.3% 95% CI=8.04-22.8) partially vaccinated. When considering the vaccination status and seroprevalence, out of the 30 fully vaccinated individuals, IgG seropositivity was 86.7% (95% CI =69.3-96.2) and IgM seropositivity was 40% (95% CI =22.7-59.4). Out of the participants that had not been vaccinated at all, IgG seroprevalence was 70.3% (95% CI 56.4-82.0) with 20.4% (95% CI 10.6-33.5) seropositivity of IgM antibodies. SARs-CoV-2 PCR positivity did not significantly predict IgG (p = 0.457 [95% CI 0.514-4.371]) and IgM (p = 0.858 [95% CI 0.350-2.395]) positivity.ConclusionOur data indicate a high seroprevalence of antibodies to SARS-CoV-2 in western Kenya. This suggests larger fraction of the population were infected with SARS-CoV-2 within the defined period than what PCR testing could cover.