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

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.

Effectiveness and Cost-Effectiveness of Inactivated Vaccine to Address COVID-19 Pandemic in China: Evidence From Randomized Control Trials and Real-World Studies

“…In the meta-analysis fixed-effects model was used when I 2 <50%, and the random-effects model was used when the I 2 > 50% to pool the VE data with 95% confidence intervals (CIs). Among the included articles, RCT evidence from Turkey ( 16 ), Brazil ( 18 , 36 ), Indonesia ( 17 ), and the United Arab Emirates and Bahrain ( 8 ); RWE data from Chile ( 9 , 30 , 34 ), Brazil ( 19 , 24 , 27 , 35 ), Argentina ( 22 ), Thailand ( 21 ), Serbia ( 23 ), United Arab Emirates ( 25 , 31 ), Iran ( 26 ), China ( 20 , 28 , 29 ), Colombia ( 33 ), Hungary, and Turkey ( 32 ) were included. As the heterogeneity among RCT and RWE was huge, and I 2 was consistently higher than 90%, this study was not able to pool efficacy and effectiveness data together; therefore, we have done subgroup analysis for RCT and RWE studies of adult, and for the elderly and children.…”

“…Among the 54 studies under full-text review, 34 studies were excluded (Figure 2). Ultimately, with four records identified through other sources included, the metaanalysis comprised 24 eligible studies finally, including four phase 3 studies (8, 16-18) and 20 real-world studies (9,(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) (including 2 RWE shared by company). The studies mentioned virus strains were as follows: four of Alpha (22,23,31,32), one of Beta (31), three of Gamma (19,22,27), five of Delta (20,21,25,28,29), one of Omicron (30), while the others did not mention the virus type.…”

The effects of inactivated SARS‐CoV‐2 vaccination and subsequent infection of pregnant mice on the behaviors of offspring

“…In the global clinical trial of ChAdOx1 nCoV‐19, the pregnancy outcome analysis of 50 women who were pregnant after vaccination showed no effect on fertility rates and pregnancy outcomes by vaccination before pregnancy 21 . The investigation of CoronaVac in pregnant women showed that two doses were 41% effective against symptomatic COVID‐19 and 85% effective against severe COVID‐19 22 . Based on the clinical safety data of pregnant women vaccination, public health institutions globally have recommended COVID‐19 vaccination for pregnant women.…”

RNA Viruses, Pregnancy and Vaccination: Emerging Lessons from COVID-19 and Ebola Virus Disease

“…In the case of COVID-19, a fourth dose of vaccine has been offered in Israel to its population above 60 years and health care workers [ 270 ], though there are reports that the fourth dose of mRNA vaccine does not offer any additional protection against new variants such as Omicron [ 271 ]. Ultimately, boosters are helpful from the perspective of the general population, but adverse immune mediated side effects should be weighed properly before widely introducing the booster doses [ 251 ]. This is particularly true in the case of immunocompromised individuals, among whom an investigation has demonstrated lower effectiveness of mRNA vaccination, in comparison to immunocompetent individuals [ 272 ].…”