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. 2023 Oct:135:109-117.
doi: 10.1016/j.ijid.2023.08.012. Epub 2023 Aug 15.

SARS-CoV-2 seroprevalence in pregnant women during the first three COVID-19 waves in The Gambia

Ramatoulie E Janha  1 , Alasana Bah  1 , Hawanatu Jah  1 , Fatima Touray  1 , Yahaya Idris  1 , Saikou Keita  1 , Yassin Gaye  1 , Samba Jallow  1 , Tisbeh Faye-Joof  1 , Baboucarr Njie  1 , Rachel Craik  2 , Nuredin I Mohammed  1 , Peter von Dadelszen  3 , Umberto D'Alessandro  1 , Anna Roca  4 ; PRECISE Network
Affiliations

SARS-CoV-2 seroprevalence in pregnant women during the first three COVID-19 waves in The Gambia

Ramatoulie E Janha et al. Int J Infect Dis. 2023 Oct.

Abstract

Objectives: SARS-CoV-2 transmission in sub-Saharan Africa has probably been underestimated. Population-based seroprevalence studies are needed to determine the extent of transmission in the continent.

Methods: Blood samples from a cohort of Gambian pregnant women were tested for SARS-CoV-2 total receptor binding domain (RBD) immunoglobulin (Ig) M/IgG before (Pre-pandemic: October-December 2019) and during the pandemic (Pre-wave 1: February-June 2020; Post-wave 1: October-December 2020, Post-wave 2: May-June 2021; and Post-wave 3: October-December 2021). Samples reactive for SARS-CoV-2 total RBD IgM/IgG were tested in specific S1- and nucleocapsid (NCP) IgG assays.

Results: SARS-CoV-2 total RBD IgM/IgG seroprevalence was 0.9% 95% confidence interval (0.2, 4.9) in Pre-pandemic; 4.1% (1.4, 11.4) in Pre-wave 1; 31.1% (25.2, 37.7) in Post-wave 1; 62.5% (55.8, 68.8) in Post-wave 2 and 90.0% (85.1, 93.5) in Post-wave 3. S-protein IgG and NCP-protein IgG seroprevalence also increased at each Post-wave period. Although S-protein IgG and NCP-protein IgG seroprevalence was similar at Post-wave 1, S-protein IgG seroprevalence was higher at Post-wave 2 and Post-wave 3, (prevalence difference 13.5 [0.1, 26.8] and prevalence ratio 1.5 [1.0, 2.3] in Post-wave 2; and 22.9 [9.2, 36.6] and 1.4 [1.1, 1.8] in Post-wave 3 respectively, P <0.001).

Conclusion: SARS-CoV-2 transmission in The Gambia during the first 3 COVID-19 waves was high, differing significantly from official numbers of COVID-19 cases reported. Our findings are important for policy makers in managing the near-endemic COVID-19.

Keywords: Antibodies; COVID-19; Pregnancy; Seroprevalence; The Gambia; sub-Saharan Africa.

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Conflict of interest statement

Declarations of Competing Interest The authors have no competing interests to declare.

Figures

Figure 1
Figure 1. SARS-CoV-2 transmission waves embedding study design.
A schematic design showing sampling time periods and sample-sizes per time period. The shadowed areas are the period of sample collection. Samples were grouped into Pre-pandemic, Pre-wave 1 and three pandemic time periods linked to the first three COVID-19 waves as Post-wave time periods. Source: https://www.moh.gov.gm/wp-content/uploads/2022/09/GMB-COVID-19-Situational-Report-452_2022_10th_24th_September_2022.pdf.
Figure 2
Figure 2. SARS-CoV-2 seroprevalence at each study period: (a) Overall; (b) Stratified by rural and urban health facilities (WANTAI test).
Chart showing SARS-CoV-2 total RBD immunoglobulin G/immunoglobulin M antibodies’ seroprevalence with 95% confidence interval (a) per time period and (b) for rural and urban Farafenni in the Post-wave time periods.
Figure 3
Figure 3. Prevalence of SARS-CoV-2 IgG sero-positivity against S-specific protein IgG and NCP-specific protein IgG.
Chart showing SARS-CoV-2 spike S1-subunit protein specific (S-IgG [blue]) and (NCP-IgG [grey]) antibodies’ prevalence and 95% confidence interval per time period. Ig, immunoglobulin; NCP, nucleocapsid protein specific; S, spike.
Figure 4
Figure 4. New infections in percentages at each of the Post-wave periods.
Chart showing percentage of new infections in seronegative individuals (and re-infections) by anti- receptor binding domain (WANTAI) test at each Post-wave time period.
See this image and copyright information in PMC

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