Seroprevalence of anti-SARS-CoV-2 antibodies in women attending antenatal care in eastern Ethiopia: a facility-based surveillance

BMJ Open. 2021 Nov 24;11(11):e055834. doi: 10.1136/bmjopen-2021-055834.

Abstract

Objective: We conducted serosurveillance of anti-SARS-CoV-2 antibodies among pregnant women attending their first antenatal care.

Setting: The surveillance was set in one referral hospital in Harar, one district hospital and one health centre located in Haramaya district in rural eastern Ethiopia.

Participants: We collected questionnaire data and a blood sample from 3312 pregnant women between 1 April 2020 and 31 March 2021. We selected 1447 blood samples at random and assayed these for anti-SARS-CoV-2 antibodies at Hararghe Health Research laboratory using WANTAI SARS-CoV-2 Rapid Test for total immunoglobulin.

Outcome: We assayed for anti-SARS-CoV-2 antibodies and temporal trends in seroprevalence were analysed with a χ2 test for trend and multivariable binomial regression.

Results: Among 1447 sera tested, 83 were positive for anti-SARS-CoV-2 antibodies giving a crude seroprevalence of 5.7% (95% CI 4.6% to 7.0%). Of 160 samples tested in April-May 2020, none was seropositive; the first seropositive sample was identified in June and seroprevalence rose steadily thereafter (χ2 test for trend, p=0.003) reaching a peak of 11.8% in February 2021. In the multivariable model, seroprevalence was approximately 3% higher in first-trimester mothers compared with later presentations, and rose by 0.75% (95% CI 0.31% to 1.20%) per month of calendar time.

Conclusions: This clinical convenience sample illustrates the dynamic of the SARS-CoV-2 epidemic in pregnant women in eastern Ethiopia; infection was rare before June 2020 but it spread in a linear fashion thereafter, rather than following intermittent waves, and reached 10% by the beginning of 2021. After 1 year of surveillance, most pregnant mothers remained susceptible.

Keywords: COVID-19; health policy; infection control; prenatal diagnosis; protocols & guidelines.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Viral
  • COVID-19*
  • Ethiopia / epidemiology
  • Female
  • Hospitals, District
  • Humans
  • Pregnancy
  • Prenatal Care*
  • SARS-CoV-2
  • Seroepidemiologic Studies

Substances

  • Antibodies, Viral