Short-term outcome of pregnant women vaccinated by BNT162b2 mRNA COVID-19 vaccine

• Published in: Ultrasound in Obstetrics & Gynecology
• Main Authors: S. Bookstein Peretz, Regev, N, Novick, L, Nachshol, M, Goffer, E, Ben-David, A, Asraf, K, Doolman, R, Sapir, E, G. Regev Yochay, Yinon, Y
• Format: Web Resource
• Language: English
• Published: Hoboken John Wiley & Sons, Inc 09.08.2021
• Subjects: COVID-19 vaccines
• DOI: 10.1002/uog.23729

Objective To determine the immunogenicity and reactogenicity of Pfizer's BNT162b2 COVID-19 vaccine among pregnant women compared with non-pregnant women, and to evaluate the obstetric outcome following vaccination. Methods An observational case-control study of pregnant women, who were vaccinated by a 2-dose regimen of BNT162b2 vaccine during gestation between January-February 2021 (study group) and were compared to age-matched non-pregnant women who received the vaccine during the same time period (control group). Participants received a digital questionnaire 1-4 weeks after the second dose and were asked to provide information regarding demographics, medications, medical history, history of prior SARS-CoV-2 infection, timing of COVID-19 vaccine doses, and side effects after each vaccine dose. A second digital questionnaire, regarding current pregnancy and delivery outcomes was sent to patients of the study group after the calculated due date. All recruited patients were offered a serology blood test for SARS-CoV-2 IgG following the second vaccination dose, and SARS CoV-2 IgG levels were compared between the two groups. Results Of 539 pregnant women who were recruited after completion of the 2-dose regimen of the vaccine, 390 returned the digital questionnaire and were included in the study group and compared to 260 age-matched non-pregnant women. The rate of most of the adverse events among pregnant women following vaccination was comparable to non-pregnant women except for myalgia, arthralgia and headache which were significantly less common among pregnant women after each dose and paresthesia, which was more common among the pregnant population after the second dose. There were no significant differences in the rates of side effects when receiving the vaccine at the first, second or third trimester of pregnancy. The rate of obstetrical complications, including uterine contractions (1.3% after the first dose and 6.4% after the second dose), vaginal bleeding (0.2% after the first dose and 1.5% after the second dose), and premature rupture of membranes (0% after the first dose and 0.7% after the second dose) were extremely low following vaccination. All maternal sera samples of both groups were positive for SARS CoV-2 IgG. However, pregnant women had significantly lower serum SARS CoV-2 IgG levels compared to non-pregnant women (27.03 vs 34.5 respectively, p<0.001). Among 57 women, who delivered during the study period median gestational age at delivery was 39.5 (IQR 38.7-40.0) weeks with no preterm birth <37 weeks and no cases of fetal or neonatal complications or death. Conclusions As shown by the adverse effect profile and short-term obstetric and neonatal outcomes, no safety signals appeared among pregnant women who were vaccinated by BNT162b2vaccine at all stages of pregnancy. The vaccine is effective in generating humoral immune response in pregnant women, although IgG levels were lower than observed in non-pregnant women.