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. 2023 Mar:6:48-57.
doi: 10.1016/j.ijregi.2022.11.011. Epub 2022 Nov 28.

High anti-SARS-CoV-2 seroprevalence among unvaccinated mother-child pairs from a rural setting in north-eastern Tanzania during the second wave of COVID-19

Omari Abdul Msemo  1 , Laura Pérez-Alós  2 , Daniel T R Minja  1 , Cecilie Bo Hansen  2 , Samwel Gesase  1 , George Mtove  1 , Joyce Mbwana  1 , Victoria Marie Linderod Larsen  2   3 , Emilie Caroline Skuladottir Bøgestad  2   3 , Louise Groth Grunnet  4 , Dirk Lund Christensen  5 , Ib Christian Bygbjerg  5 , David Burgner  6   7 , Christentze Schmiegelow  8   9 , Peter Garred  2 , Line Hjort  10   10
Affiliations

High anti-SARS-CoV-2 seroprevalence among unvaccinated mother-child pairs from a rural setting in north-eastern Tanzania during the second wave of COVID-19

Omari Abdul Msemo et al. IJID Reg. 2023 Mar.

Abstract

Background: The reported infection rates and burden of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in low- and middle-income countries, including those in sub-Saharan Africa, are relatively low compared to the rates and burden in Europe and America, partly due to limited testing capability. Unlike many countries, Tanzania has implemented neither mass screening nor restrictive measures such as lockdowns to date. The prevalence of SARS-CoV-2 infection in rural mainland Tanzania is largely unknown.

Methods: A cross-sectional study was conducted between April and October 2021 to assess the anti-SARS-CoV-2 seroprevalence among mother-child pairs (n = 634 children, n = 518 mothers) in a rural setting in north-eastern Tanzania.

Results: A very high prevalence of anti-SARS-CoV-2 antibody titres was found, with seroprevalence rates ranging from 29% among mothers and 40% among children, with a dynamic peak in seropositivity incidence at the end of July/early August being revealed. Significant differences in age, socioeconomic status, and body composition were associated with seropositivity in mothers and children. No significant associations were observed between seropositivity and comorbidities, including anaemia, diabetes, malaria, and HIV.

Conclusions: The transmission of SARS-CoV-2 in a rural region of Tanzania during 2021 was high, indicating a much higher infection rate in rural Tanzania compared to that reported in the UK and USA during the same period. Ongoing immune surveillance may be vital to monitoring the burden of viral infection in rural settings without access to molecular genotyping, where the load of communicable diseases may mask COVID-19. Surveillance could be implemented in tandem with the intensification of vaccination strategies.

Keywords: Anti-SARS-CoV-2; Immune surveillance; Low- and middle-income countries; Rural; Seroprevalence; Sub-Saharan Africa; Tanzania; Vaccination.

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Figures

Figure 1
Figure 1
Anti-SARS-CoV-2 seroprevalence of total immunoglobulin against SARS-CoV-2 RBD of the spike protein in (A) children aged 5–12 years, and (B) mothers aged 21–59 years. An average of seven children and six mothers were examined on each date. Exact numbers of individuals by date are shown in Supplementary Material Figure S1.
Figure 2
Figure 2
Overview of the villages included in the study. Korogwe village consists of seven smaller city areas that are not shown on the map: Kilole, Magundi, Majengo, Manundu, Masuguru, Mtonga, and Old Korogwe.
Figure 3
Figure 3
Quantitative determination of IgG antibody levels and neutralizing antibodies against RBD in anti-SARS-CoV-2 seropositive individuals. (A) IgG levels (log(AU/ml)) in mothers aged 21–59 years and children aged 5–12 years. (B) Levels of neutralizing antibodies (log(IU/ml)) measured in mothers aged 21–59 years and children aged 5–12 years. The horizontal dashed line represents the assay positivity threshold. A p-value <0.05 was considered statistically significant; **p < 0.01 by Mann–Whitney U-test.
See this image and copyright information in PMC

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