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

The 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. The 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 29.6% (95% CI = 20.8–39.7) respectively. In terms of gender, males had slightly higher IgG positivity 87.5% (35/40) than females 68.9% (40/58). 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, (31.6%, 95% CI = 22.6–41.8) of the study participants had been fully vaccinated, with close to a quarter (13.3% 95% CI = 7.26–21.6) partially vaccinated. When considering the vaccination status and seroprevalence, out of the 31 fully vaccinated individuals, IgG seropositivity was 81.1% (95% CI = 70.2–96.3) and IgM seropositivity was 35.5% (95% CI = 19.22–54.6). Out of the participants that had not been vaccinated at all, IgG seroprevalence was 70.4% (95% CI 56.4–82.0) with 20.4% (95% CI 10.6–33.5) seropositivity for IgM antibodies. On PCR testing, 33.7% were positive, with 66.3% negative. The 32 positive individuals included 12(37.5%) fully vaccinated, 8(25%) partially vaccinated and 12(37.5%) unvaccinated. SARs-CoV-2 PCR positivity did not significantly predict IgG (p = 0.469 [95% CI 0.514–4.230]) and IgM (p = 0.964 [95% CI 0.380–2.516]) positivity. These data indicate a high seroprevalence of antibodies to SARS-CoV-2 in western Kenya. This suggests that a larger fraction of the population was infected with SARS-CoV-2 within the defined period than what PCR testing could cover.

High pre‐Delta and early‐Omicron SARS‐CoV‐2 seroprevalence detected in dried blood samples from Kinshasa (D.R. Congo)

“…This finding is in agreement with others at a similar time in the continent: serosurveys in Cameroon, Gambia, Uganda and South Africa have reported antibody positivity between 87% and 96% during the Omicron wave 16,17,19,50,54 . Although lower, the 76.5% seroprevalence reported in Kenya by Awandu et al greatly surpasses PCR confirmed cases 25 . A 2022 rapid‐assay based survey in the Republic of the Congo reported a much lower seroprevalence (48.2%) 15 .…”

“…A recent study in Uganda found that 85% of previously negative participants had detectable antibody levels post‐Omicron 54 . It has been suggested that this drastic increase could have been favored by a reduction in perceived danger and pandemic fatigue, 25 as the rate of transmission is highly related to population density, hygiene, and the observation of nonpharmacological interventions. Nevertheless, adherence to these public health measures was generally low in the DRC, however, higher in the capital than in other regions 56 …”

“…In contrast, studies in the DRC have found seroprevalences ranging from 48% 12 to 70% 13,14 . A similar phenomenon has occurred in neighboring countries such as Republic of the Congo, 15 Cameroon, 16 Gambia, 17 Somalia, 18 Uganda, 12,14,19 Tanzania, 20 Nigeria 12,21,22 and Kenya, 23–25 where growing evidence indicates pandemic burden has been grossly underestimated.…”

“…A recent study in Uganda found that 85% of previously negative participants had detectable antibody levels post-Omicron. 54 It has been suggested that this drastic increase could have been favored by a reduction in perceived danger and pandemic fatigue, 25 as the rate of transmission is highly related to population density, hygiene, and the observation of T A B L E 3 Analytic performance of ECLIA and CLIA assays using Dried Blood Spots (DBS). by 2022.…”

Trends in SARS-CoV-2 seroprevalence among pregnant women attending first antenatal care visits in Zambia: a repeated cross-sectional survey, 2021-2022

“…26 Other studies in Africa also measured higher SARS-CoV-2 seroprevalence among vaccinated participants, higher neutralizing antibody titers among participants with infection and vaccination, and faster waning of antibodies post-vaccination among participants who had not been infected. 7,27–29 These results support the recommendation for COVID-19 vaccination (including booster doses) regardless of past infection. COVID-19 vaccination campaigns were conducted throughout Zambia during the study period, but vaccine coverage among study participants was lower than the general population, possibly reflecting hesitancy toward vaccination during pregnancy, and only about 12% of the fully vaccinated population has received a booster dose.…”