Studying an Understudied Population in a Time of Crisis and Conflict

Posted on 17.08.2023

A study found a very high seroprevalence of SARS-CoV-2 antibodies in mother-children pairs in rural north-eastern Tanzania. Line Hjort shares her insights from the study, as well as from her time doing research in Tanzania while the country’s government was downplaying the COVID-19 pandemic.

During the first year of the COVID-19 pandemic, Tanzania’s then government refused to recognise the severity of the virus. Some Tanzanian researchers persisted in studying the virus, albeit with great caution.

The results of one such study published earlier this year found a high prevalence of SARS-CoV-2 antibodies among unvaccinated mother-child pairs during the second wave of COVID-19 in rural north-eastern Tanzania.

Changing Course in a Pandemic

The article 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 was published in IJID Regions in March.

Line Hjort, who is listed as the last author of the article, is a formerly Danish Diabetes Academy-funded researcher with a Master’s degree in human biology. Line went to Tanzania in 2021 for research during the COVID-19 pandemic.

The Tanzanian government was reported to severely downplay the gravity of the virus, which made research into COVID-19 difficult.

Line Hjort with her colleagues from Tanzania

– This study was not at all part of the original study protocol, but because the COVID-19 pandemic occurred during our data collection, we felt that we needed to assess the prevalence of this viral epidemic in our study cohort. This was in our opinion highly important because Tanzania, due to political reasons, did not screen or test for COVID in the first year of the pandemic. Therefore, our study was the first to be able to assess COVID-19 seroprevalence in a large rural population of both children and mothers in Tanzania, explains Line Hjort.

Seroprevalence is the number of persons in a population who test positive for a specific disease based on serology (blood serum) specimens

An Understudied Population

Line and her colleagues did a cross-sectional study between April and October 2021 in which they, together with the Department of Clinical Immunology at Rigshospitalet, assessed the anti-SARS-CoV-2 seroprevalence among mother-child pairs, comprising 518 mothers and 634 children.

– We found an extremely high seroprevalence in both children (40%) and mothers (29%) that were up to 10 times higher than what was observed in the same age groups in for example Denmark at the same time. Also interestingly, we found that girls were more likely to have had previous COVID-19 than boys, and we observed that lower socioeconomic status was associated with the seropositivity, says Line Hjort.

Figure 1: Anti-SARS-CoV-2 seroprevalence of total Ig against SARS-CoV-2 RBD of the spike protein in A) children age 5-12 years, and B) mothers aged 21-59 years. Number of individuals examined each date was on average seven children and six mothers. Exact numbers of individuals by date are shown in Supplementary Figure 1.

These numbers are significant considering that Tanzania at the time hardly reported any cases of COVID-19.

– Since the publication of the study, we have generally received responses that the seropositivity was surprisingly high, especially since almost no reports of COVID-19 in Tanzania had been reported through international health surveillance communities in the time period we conducted the study, says Line Hjort.

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.

She continues:

– This is such an understudied population, and we have so many knowledge gaps in our research in health and disease because ethnicity and population differences are missing. Yet, at the same time, they are very important to recognise to ensure that for example the limited healthcare resources in rural regions in Tanzania are being used most appropriately, says Line Hjort.

Research in a Politically Stirred Landscape

In a statement from the WHO Director-General to Tanzania from February 2021, the Tanzanian government was urged to take “robust action” to start reporting COVID-19 cases and implement public health measures.

All in all, this seems to have been a difficult time to be a health researcher in Tanzania, which Line Hjort confirms, as she saw her colleagues in Tanzania struggle while still seeing great importance in researching COVID-19 prevalence.

The Tanzanian government has since changed and with it, the position on the virus changed, with measures taken to strengthen outreaches and public health education. WHO reported on Tanzania’s road to the “big catch-up” of vaccination, asserting Tanzania as the best performing among 34 African countries for intense support by the COVID-19 Vaccine Delivery Partnership.

Line Hjort states that this change has also greatly benefited her colleagues’ research in Tanzania.

– I know that the Tanzanian health ministry now supports Tanzanian researchers in doing COVID-19 research and surveillance. I don’t know if this is linked to our study, but one of my Tanzanian colleagues is now leading a government-funded research project on COVID-19 in the very same region, explains Line Hjort.

Hopes to Inspire Greater Focus on Women’s and Children’s Health

Line Hjort’s PhD project focused on epigenetics mechanisms in gestational diabetes and foetal development at the obstetrics department at Rigshospitalet.

Line aims to generate results that can help secure a healthy life for children who have experienced an unfavourable environment in the womb or early in life.

– We hope this research can inspire a larger focus on women’s and children’s health during the COVID pandemic, especially for more vulnerable populations with no free access to healthcare, says Line Hjort.

Line Hjort is currently working on her second postdoc project as part of the BRIDGE program at the University of Copenhagen, where she is based at the Center for Metabolic Research (CBMR) in the Barrés Lab.


Covid: Does Tanzania have a hidden epidemic? – BBC

Covid: WHO pleads with Tanzania to start reporting cases – BBC

WHO Director-General’s statement on Tanzania and COVID-19

Tanzania’s road to the “big catch up” of routine vaccination

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

IJID Regions, Mar, 2023, doi: 10.1016/j.ijregi.2022.11.011

Written by Omari Abdul Msemo, Laura Pérez-Alós, Daniel T.R. Minja, Cecilie Bo Hansen, Samwel Gesase, George Mtove, Joyce Mbwana, Victoria Marie Linderod Larsen, Emilie Caroline Skuladottir Bøgestad, Louise Groth Grunnet, Dirk Lund Christensen, Ib Christian Bygbjerg, David Burgner, Christentze Schmiegelow, Peter Garred*, and Line Hjort*.

*Shared last authorship.

Contact Information

Line Hjort
Postdoctoral researcher
BRIDGE – Translational Excellence Programme, University of Copenhagen, The Novo Nordisk Foundation Center for Basic Metabolic Research

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