Assessment of acute adverse events after vaccination with Covid-19 during pregnancy

To the editor:

Pregnant women with symptomatic coronavirus disease (Covid-19) in 2019 are at increased risk of adverse consequences than non-pregnant women.1,2 Due to these findings, Covid-19 vaccination is recommended for pregnant women. However, pregnant women consume less than non-pregnant women.3,4 Many women’s safety concerns remain a barrier to maternal vaccination.

From December 15, 2020 to July 1, 2021, eight vaccine safety data link sites conducted retrospective observational studies of pregnant women aged 16 to 49 years. Each dose of the Food and Drug Administration was matched. – An approved Covid-19 vaccine that pregnant women received for unvaccinated pregnant women, depending on the study site and the date of onset of pregnancy. The pregnancy cohort included women who were found to be pregnant within 28 days of vaccination. Vaccinations were obtained through electronic health records, billing data, and bidirectional links with state and local immune registries.Five

Incidence of 25 Medically Participated Acute Adverse Events (Known Responsive Adverse Events and Clinically Serious Results) Among Vaccinated Women Compared to Unvaccinated Matched Controls Was evaluated. The primary analysis focused on events that occur within 21 days of vaccination. Secondary analysis included events that occurred within 42 days after the second dose of messenger RNA (mRNA) vaccine (either BNT162b2). [Pfizer–BioNTech] Or mRNA-1273 [Moderna] Vaccines) (Appendix Table S4, available at with the full text of this letter). After applying stabilized inverse probability weighting to the tendency to be vaccinated, Poisson regression was used to estimate the adjusted ratio. Additional details about statistical methods can be found in the supplementary appendix.

We identified 45,232 pregnant women who received one or two doses of the Covid-19 vaccine shortly before or during pregnancy (78,026 vaccinations) (Figure S1). Of these women, 32,794 (72.5%) received two mRNA vaccines, 5652 (12.5%) received only the first mRNA vaccine, and 4912 (10.9%) received the second mRNA vaccine. I received only the inoculation of. In 1874 (4.1%), he received a single dose of the Ad26.COV2.S vaccine (Johnson & Johnson–Janssen). (Women who received only the second vaccination received the first vaccination more than 28 days before becoming pregnant.) The percentage of women who received the first vaccination was 30-49 years old. He was a non-Hispanic Caucasian or a non-Hispanic Asian. Compared to unvaccinated women (Table S4).

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Medically attended acute adverse events during pregnancy (December 15, 2020-July 1, 2021), according to receipt or non-receipt of the Covid-19 vaccine.

Shown are medicine in 45,232 pregnant women who received one or two Covid-19 vaccines (78,026 vaccines) and the corresponding unvaccinated controls immediately before or during pregnancy. It is the incidence of acute adverse events that participated in the pregnancy. The rate of adverse events per 10,000 vaccinations was calculated for vaccinated women and was consistent with the rate of unvaccinated controls. Data were evaluated within 21 days of vaccination at eight vaccine safety data link sites. Acute disseminated encephalomyelitis, cerebral sinus thrombosis, disseminated intravascular coagulation syndrome, encephalitis or myelitis, Gillan-Barre syndrome, myocarditis or peritonitis, hemorrhagic or ischemic stroke, Stevens-Johnson syndrome or There were no reports of a pre-designated list of adverse events, including toxicity: epidermal necrosis, thrombosis with thrombocytopenia syndrome, thrombosis, thrombotic thrombocytopenic purpura, or pulmonary embolism. Anaphylaxis was evaluated only in the vaccinated group and no confirmed cases have been reported.

The frequency of all medically attended acute adverse events was less than 1%.Among vaccinated individuals, the most common event was fever (adjusted rate ratio compared to unvaccinated controls, 2.85; 95% confidence interval. [CI]1.76 to 4.61), malaise or malaise (adjustment ratio, 2.24; 95% CI, 1.71 to 2.93), local response (adjustment ratio, 1.89; 95% CI, 1.33 to 2.68), and lymphadenopathy or Lymphadenitis (adjustment ratio, 2.16; 95% CI, 1.42 to 3.28) (Figure 1). Serious acute adverse events assessed (eg, cerebral venous sinus thrombosis, encephalitis or myelitis, Gillan Valley syndrome, myocarditis or peritonitis, or pulmonary embolism) are vaccinated in vaccinated women. It occurred less frequently than the unvaccinated control group. Subgroup analyzes comparing the incidence of results in the two groups showed similar overall associations (Tables S4 and S5 and Figures), as stratified according to vaccine dose and mRNA vaccine manufacturer. S3 and S4). The limits of the study are the potential underestimation of the outcome rate when the actual risk interval differs from the 21-day or 42-day interval used, the presence of wide confidence intervals around some rate ratios, and Covid. Included potential misclassification or incomplete capture of. 19 Vaccine exposure or other covariates.

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Medically-participated acute adverse events shortly before or after Covid-19 vaccination during pregnancy were rare. The Covid-19 vaccine was not associated with an increased risk of clinically serious acute adverse events evaluated. Current data will be added to the growing literature supporting the safety of Covid-19 vaccination during pregnancy.

Malini DeSilva, MD
Jacob Harpara, MPH
Gabriela Vazquez-Benitez, Ph.D.
HealthPartners Institute, Bloomington, Minnesota
[email protected]

Kimberly K. Besco, MD
Kaiser Permanente Northwest, Portland, Oregon

Matthew F. Daily, MD
Kaiser Permanente Colorado, Denver, Colorado

Darios Getahun, MD, Ph.D.
Kaiser Permanente Southern California, Pasadena, California

Ousseny Zerbo, Ph.D.
Kaiser Permanente Vaccine Research Center, Oakland, CA

Dr. Alison Naleway
Kaiser Permanente Northwest, Portland, Oregon

Dr. Jennifer C. Nelson
Kaiser Permanente Washington, Seattle, WA

Joshua TB Williams, MD
Simon J. Hambidge, MD, Ph.D.
Denver Health, Denver, Colorado

Thomas G. Voice, MD
Marshfield Clinic, Marshfield, Wisconsin

Dr. Candice C. Fuller, MPH
Harvard Pilgrim Healthcare Institute, Boston, Massachusetts

Heather S. Lipkind, MD
Yale School of Medicine, New Haven, Connecticut

Eric Waitraub, MPH
Michael M. McNeil, MD
Centers for Disease Control and Prevention, Atlanta, Georgia

Ellis O. Karlbanda, MD
HealthPartners Institute, Bloomington, Minnesota

Supported by contract with (200-2012-53526) CDC..

The disclosure form provided by the author is available on with the full text of this letter.

The views expressed in this letter are those of the author and do not necessarily represent the official position of the Centers for Disease Control and Prevention (CDC). Product or company names are for identification purposes only and do not constitute CDC approval.

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This letter was published on June 22, 2022 at

  1. 1.1. Ellington S, Stride P, Ton VT,other. Characteristics of women of reproductive age with SARS-CoV-2 infection confirmed by pregnancy status — USA, January 22-7, 2020. MMWRMorb Mortal Wkly Rep 202069:769――――775..

  2. 2.2. Zambrano LD, Ellington S, Stride P,other. Update: Characteristics of symptomatic females of reproductive age with SARS-CoV-2 infection confirmed in the laboratory by pregnancy status — January 22, 2020-October 3, 2020, USA. MMWRMorb Mortal Wkly Rep 202069:1641――――1647..

  3. 3.3. Centers for Disease Control and Prevention. COVID-19 vaccine during pregnancy or lactation. 2022 (Https://

  4. 4.4. Theiler RN, Wick M, Meta R, Weaver AL, function, Swift M.. Results of pregnancy and childbirth after SARS-CoV-2 vaccination during pregnancy. Am J Obstet Gynecol MFM 2021; 3:100467――――100467..

  5. 5.5. Groom HC, Crane B, Nareway AL,other. Vaccine Safety Monitoring Using Vaccine Safety Data Links: An assessment of the ability to integrate data from immunized information systems.vaccination 202240:752――――756..

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