Early exploration of COVID-19 vaccination safety and effectiveness during pregnancy: interim descriptive data from a prospective observational study

Abstract

Objective During December 2020, a massive vaccination program was introduced in our country. The Pfizer-BioNTech, BNT162b2 vaccine was first offered exclusively to high-risk population, such as medical personnel (including pregnant women). In this study we compare short term outcomes in vaccinated vs. non-vaccinated pregnant women. Methods In this prospective observational cohort study, vaccinated and non-vaccinated pregnant women were recruited using an online Google forms questionnaire targeting medical groups on Facebook and WhatsApp. A second questionnaire was sent one month after the first one for interim analysis. Our primary outcome was composite complications in vaccinated and non-vaccinated groups, considered any of the following: vaginal bleeding, pregnancy loss, hypertension, gestational diabetes, and preterm birth. Secondary outcomes included: vaccine side effects, diagnosis of COVID-19 since the last questionnaire, prevalence of vaccinated participants, and reasons for refusal to be vaccinated. Results Overall, 432 women answered the first questionnaire, of which 326 responses were received to the second questionnaire. Vaccination rate increased from 25.5% to 62% within a month. Maternal age, gestational age at enrollment, nulliparity and number of children were similar in both groups. The rate of composite pregnancy complications was similar between vaccinated and non-vaccinated group (15.8% vs 20.1%, p=0.37), respectively. The risk for COVID-19 infection was significantly lower in the vaccinated group (1.5% vs 6.5%, p=0.024, Odds Ratio: 4.5, 95% confidence interval 1.19-17.6). Conclusions mRNA vaccine during pregnancy does not seem to increase the rate of pregnancy complications and is effective in prevention of COVID-19 infection.

Systematic review and meta-analysis of the effectiveness and perinatal outcomes of COVID-19 vaccination in pregnancy

“…Three observational studies 22 – 24 examined the effectiveness of mRNA vaccination against SARS-CoV-2 infection, comparing 18,828 vaccinated pregnant people and 18,828 unvaccinated pregnancy controls. While other studies reported on SARS-CoV-2 infection 20 , 30 as an outcome measure, the duration of follow-up and accounting strategy of time-varying confounding were unclear, so they were not included in the quantitative summary.…”

“…Of 18 observational studies of the impact of COVID-19 vaccination (vs. no vaccination) on pregnancy outcomes, the vast majority were of mRNA vaccines, with very few of viral vector vaccines 8 , 21 , 26 – 30 , 33 . Twelve studies were observational 8 , 19 , 20 , 22 – 24 , 27 , 29 – 32 , 34 and three were governmental reports 21 , 28 , 33 . We did not include two studies reporting vaccination side-effects 13 , 26 and a single study 25 reporting antibody levels, as there was no pregnancy control group.…”

“…We did not include two studies reporting vaccination side-effects 13 , 26 and a single study 25 reporting antibody levels, as there was no pregnancy control group. Three studies were at overall serious risk of bias 19 , 20 , 32 , with the remainder at moderate risk 8 , 13 , 21 – 34 (Supplementary Tables 3 and 4). No study was deemed to be at risk of bias for classification of interventions or deviation from intended interventions domains.…”

“…Although miscarriage rate was reported in multiple studies 20 , 24 , 27 , 29 , only two compared vaccinated and unvaccinated populations and accounted for time-varying confounding 27 , 29 . The pooled odds ratio meta-analysis showed no significant effect of vaccination on miscarriage (pooled OR 1.00; 95% CI 0.92–1.09, 15,684 vaccinated vs. 108,249 unvaccinated population, P = 0.988, I 2 = 19.8%, Fig.…”

SARS-CoV-2 Vaccines during Pregnancy and Breastfeeding: A Systematic Review of Maternal and Neonatal Outcomes

“…A flowchart of study selection process is reported in Figure 2 . We considered 46 records: 30 of them included pregnant mothers [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ], two studies included both pregnant and lactating mothers [ 39 , 40 ], and 14 studies included lactating mothers [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. Most studies were conducted in the United States (41.3%) and Israel (26.1%), along with three in Italy (6.5%), two in Spain (4.3%) and in Poland (4.3%), and the remaining (17.2%) in the United Kingdom, Qatar, Belgium, Germany, Norway, Portugal, the Netherlands, and Singapore.…”