• Enny S Paixao, Kerry L M Wong, AlvesFlavia Jôse OliveiraFJOCenter of Data and Knowledge Integration for Health (CIDACS), Gonçalo Moniz Institute, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil., 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, and Manoel Barral-Netto.
• London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK. enny.cruz@lshtm.ac.uk.
• Bmc Med. 2022 Apr 5; 20 (1): 146146.

BackgroundMore 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.MethodsWe 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.ResultsOf 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.ConclusionsA 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.© 2022. The Author(s).

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