BMC Medicine (Apr 2022)

CoronaVac vaccine is effective in preventing symptomatic and severe COVID-19 in pregnant women in Brazil: a test-negative case-control study

  • Enny S. Paixao,
  • Kerry L. M. Wong,
  • Flavia Jôse Oliveira Alves,
  • Vinicius de Araújo Oliveira,
  • Thiago Cerqueira-Silva,
  • Juracy Bertoldo Júnior,
  • Tales Mota Machado,
  • Elzo Pereira Pinto Junior,
  • Viviane S. Boaventura,
  • Gerson O. Penna,
  • Guilherme Loureiro Werneck,
  • Laura C. Rodrigues,
  • Neil Pearce,
  • Mauricio L. Barreto,
  • Manoel Barral-Netto

DOI
https://doi.org/10.1186/s12916-022-02353-w
Journal volume & issue
Vol. 20, no. 1
pp. 1 – 8

Abstract

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Abstract Background More doses of CoronaVac have been administered worldwide than any other COVID-19 vaccine. However, the effectiveness of COVID-19 inactivated vaccines in pregnant women is still unknown. We estimated the vaccine effectiveness (VE) of CoronaVac against symptomatic and severe COVID-19 in pregnant women in Brazil. Methods We conducted a test-negative design study in all pregnant women aged 18–49 years with COVID-19-related symptoms in Brazil from March 15, 2021, to October 03, 2021, linking records of negative and positive SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) tests to national vaccination records. We also linked records of test-positive cases with notifications of severe, hospitalised or fatal COVID-19. Using logistic regression, we estimated the adjusted odds ratio and VE against symptomatic COVID-19 and against severe COVID-19 by comparing vaccine status in test-negative subjects to test-positive symptomatic cases and severe cases. Results Of the 19,838 tested pregnant women, 7424 (37.4%) tested positive for COVID-19 and 588 (7.9%) had severe disease. Only 83% of pregnant women who received the first dose of CoronaVac completed the vaccination scheme. A single dose of the CoronaVac vaccine was not effective at preventing symptomatic COVID-19. The effectiveness of two doses of CoronaVac was 41% (95% CI 27.1–52.2) against symptomatic COVID-19 and 85% (95% CI 59.5–94.8) against severe COVID-19. Conclusions A complete regimen of CoronaVac in pregnant women was effective in preventing symptomatic COVID-19 and highly effective against severe illness in a setting that combined high disease burden and marked COVID-19-related maternal deaths.

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