Spontaneous Abortion Following COVID-19 Vaccination During Pregnancy (JAMA 2021.9.8)

COVID-19 infection during pregnancy can be associated with severe maternal morbidity. In the United States, 1 COVID-19 vaccine has been approved and 2 have been authorized for use for pregnant women. To date, data on maternal COVID-19 vaccine safety come primarily from passive surveillance, and studies lack an unvaccinated comparison group. Spontaneous abortion has been identified as a priority outcome in studies of maternal vaccine safety, and concerns regarding risks of spontaneous abortion may be a barrier to vaccination during pregnancy. We present findings from case-control surveillance of COVID-19 vaccination during pregnancy and spontaneous abortion.


The Vaccine Safety Datalink is a collaboration between the Centers for Disease Control and Prevention and 9 health systems, representing approximately 3% of the US population. We applied a validated pregnancy algorithm, which incorporates diagnostic and procedure codes and electronic health record (EHR) data, to identify and assign gestational ages for spontaneous abortions and ongoing pregnancies. Data from 8 health systems (Kaiser Permanente: Washington, Northwest, Northern California, Southern California, and Colorado; Denver Health; HealthPartners; and Marshfield Clinic, Wisconsin) over seven 4-week surveillance periods from December 15, 2020, through June 28, 2021, were included.



Of 105 446 unique pregnancies, 13 160 spontaneous abortions and 92 286 ongoing pregnancies were identified. Overall, 7.8% of women received 1 or more BNT162b2 (Pfizer-BioNTech) vaccines; 6.0% received 1 or more mRNA-1273 (Moderna) vaccines; and 0.5% received an Ad26.COV.2.S (Janssen) vaccine during pregnancy and before 20 weeks' gestation. The proportion of women aged 35 through 49 years with spontaneous abortions was higher (38.7%) than with ongoing pregnancies (22.3%). A COVID-19 vaccine was received within 28 days prior to an index date among 8.0% of ongoing pregnancy periods vs 8.6% of spontaneous abortions (Table 1). Spontaneous abortions did not have an increased odds of exposure to a COVID-19 vaccination in the prior 28 days compared with ongoing pregnancies (adjusted odds ratio, 1.02; 95% CI, 0.96-1.08). Results were consistent for mRNA-1273 and BNT162b2 and by gestational age group (Table 2).


Among women with spontaneous abortions, the odds of COVID-19 vaccine exposure were not increased in the prior 28 days compared with women with ongoing pregnancies. Strengths of this surveillance include the availability of a multisite diverse population with robust data capture. Several limitations should be noted. First, gestational age of spontaneous abortions and ongoing pregnancies were not chart confirmed; pregnancy dating may be inaccurate early in pregnancy. Second, although vaccination status was identified using multiple data sources, the COVID-19 vaccine rollout has been complex and some vaccines may have been missed, potentially biasing findings to the null. Third, data on important confounders, such as prior pregnancy history, were not available. Fourth, it was not possible to assess risks specific to the Ad26.COV.2.S vaccine given the small number of exposures. Despite limitations, these data can be used to inform vaccine recommendations and to counsel patients.

妊娠中のCOVID-19ワクチン接種後の自然流産(JAMA 2021.9.8)

妊娠中のCOVID-19感染は,母体の重篤な病的状態と関連する可能性がある。米国では,妊娠中の女性に対し、1 種類の COVID-19 ワクチンが使用を承認され,2 種類のワクチンが許可されている。現在までのところ、COVID-19ワクチンの母親への安全性に関するデータは主にパッシブサーベイランスによるもので、研究にはワクチンを接種していない比較群がない。自然流産は,母親のワクチン安全性に関する研究において優先される結果とされており,自然流産のリスクに関する懸念が,妊娠中のワクチン接種の障壁となっている可能性がある。妊娠中のCOVID-19ワクチン接種と自然流産に関するケースコントロールサーベイランスの結果を報告する。


Vaccine Safety Datalinkは,米国疾病対策センター(Centers for Disease Control and Prevention)と9つの医療機関との共同研究であり、米国人口の約3%に相当する。自然流産と継続中の妊娠の妊娠期間を特定して割り当てるために,診断および処置規則,電子カルテ(EHR)データを組み込んだ有効な妊娠アルゴリズムを適用した。8つの医療機関のデータ(Kaiser Permanente: ワシントン州、北西部、北カリフォルニア、南カリフォルニア、コロラド州、Denver Health、HealthPartners、ウィスコンシン州Marshfield Clinic)の8つのヘルスシステムから、2020年12月15日から2021年6月28日までの7つの4週間の調査期間のデータを対象とした。






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