V-safe Surveillance: Local and Systemic Reactogenicity in Pregnant Subjects
Characteristics of Subjects Who Identified as Pregnant in the V-Safe Surveillance System and Received an mRNA Covid-19 Vaccine. 
Frequency of local and systemic reactions reported the day after Covid-19 mRNA vaccination in pregnant subjects.
From December 14, 2020 to February 28, 2021, a total of 35,691 v-safe participants were identified as pregnant. The age distributions were similar between the participants who received the Pfizer-BioNTech vaccine and those who received the Moderna vaccine, with the majority of the participants being 25 to 34 years old (61.9% and 60.6% for each vaccine, respectively ) and non-Hispanic White (76.2% and 75.4%, respectively); most participants (85.8% and 87.4%, respectively) reported being pregnant at the time of vaccination (table 1). Solicited reports of pain, fatigue, headache and muscle pain at the injection site were the most frequent local and systemic reactions after each dose for both vaccines (table 2) and reported more frequently after dose 2 for both vaccines. Participant-measured temperatures at or above 38 ° C were reported by less than 1% of participants on day 1 after dose 1 and by 8.0% after dose 2 for both vaccines.
Most frequent local and systemic reactions reported in the V-safe Surveillance System on the day after Covid-19 mRNA vaccination.
Shown are solicited responses in pregnant subjects and non-pregnant women aged 16 to 54 years who received messenger RNA (mRNA) coronavirus disease 2019 (Covid-19) vaccine – BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) – from December 14, 2020, to February 28, 2021. The percentage of respondents is calculated among those who completed a Day 1 survey, the main events of which were injection site pain (pain), fatigue or fatigue (fatigue), headache, muscle or body aches (myalgia), chills, and fever or feverish feeling (fever).
These reporting patterns, with respect to both the most frequently reported solicited responses and the higher reporting of reactogenicity after dose 2, were similar to those observed in non-pregnant women (Figure 1). Small differences in reporting frequency between pregnant subjects and non-pregnant women were observed for specific reactions (injection site pain was more frequently reported in pregnant subjects and other systemic reactions were more frequently reported in non-pregnant women), but the overall reactogenicity profile was similar. Pregnant subjects were no more likely to report serious reactions than non-pregnant women, with the exception of nausea and vomiting, which were only reported slightly more frequently after dose 2 (Table S3).
V-Safe Pregnancy Registry: Pregnancy Outcomes and Neonatal Outcomes
Characteristics of participants in the V-safe pregnancy registry.
As of March 30, 2021, the v-safe pregnancy registry call center attempted to contact 5,230 individuals vaccinated through February 28, 2021 who determined in a v-safe survey that they were pregnant on or shortly after the Covid -19 vaccination. Of these, 912 were unreachable, 86 declined to participate, and 274 did not meet the inclusion criteria (e.g., were never pregnant, were pregnant but received vaccination more than 30 days before the last menstrual period, or did not provide enough information to determine whether were eligible). The registry enrolled 3,958 participants with vaccination from December 14, 2020 to February 28, 2021, of whom 3,719 (94.0%) identified as medical personnel. Among the enrolled participants, most were 25 to 44 years old (98.8%), non-Hispanic White (79.0%), and did not report a Covid-19 diagnosis in pregnancy at the time of the interview (97.6 %) (table 3). The receipt of a first dose of vaccine meeting the eligibility criteria for the registry was reported by 92 participants (2.3%) during the perception period, by 1132 (28.6%) in the first trimester of the pregnancy, by 1,714 (43.3%) in the second trimester, and by 1,019 (25.7%) in the third trimester (1 participant lacked information to determine the timing of vaccination) (table 3). Of the 1040 participants (91.9%) who received a vaccine in the first trimester and 1700 (99.2%) who received a vaccine in the second trimester, the first data had been collected and follow-up was scheduled at designated times approximately 10 to 12 weeks apart; At the time of this analysis, there were limited follow-up interviews.
Pregnancy Loss and Neonatal Outcomes in Published Studies and Participants in V-safe Pregnancy Registry.
Of the 827 participants who had completed pregnancy, the pregnancy resulted in a live birth in 712 participants (86.1%), in 104 in a spontaneous abortion (12.6%), in 1 stillbirth (0.1%) and in other outcomes (induced abortion). and ectopic pregnancy) at 10 (1.2%). A total of 96 of 104 spontaneous abortions (92.3%) occurred before 13 weeks of gestation (Table 4), and 700 of the 712 pregnancies that resulted in a live birth (98.3%) were among those who received their first eligible vaccine dose in the third trimester. Adverse drug reactions in 724 live-born infants – including 12 sets of multiple pregnancies – were preterm birth (60 of 636 among those vaccinated before 37 weeks) [9.4%]), small size for gestational age (23 of 724 [3.2%]) and serious birth defects (16 of 724 [2.2%]); no neonatal deaths were reported at the time of the interview. Of the participants with completed pregnancies who reported birth defects, none had received the Covid-19 vaccine in the first trimester or the perception period, and no specific pattern of birth defects was observed. The calculated proportions of pregnancy and neonatal outcomes appeared to be comparable to incidents published in the peer-reviewed literature (Table 4).
Findings on adverse events about the VAERS
During the analysis period, the VAERS received and processed 221 reports of vaccination with Covid-19 among pregnant individuals; 155 (70.1%) were related to non-pregnancy specific adverse reactions and 66 (29.9%) concerned pregnancy or neonatal specific adverse reactions (Table S4). The most frequently reported pregnancy-related adverse events were spontaneous abortion (46 cases; 37 in the first trimester, 2 in the second trimester, and 7 in which the trimester was unknown or not reported), followed by stillbirth, premature rupture of the membranes, and vaginal bleeding, with 3 reports each. No birth defects were reported to the VAERS, a requirement under the EUAs.