COVID-19 caused by the omicron variant (B.1.1.529) during pregnancy is associated with increased maternal morbidity and mortality, particularly in women who are symptomatic or unvaccinated, according to the results of the INTERCOVID-2022 study. “Women with complete or boosted vaccine doses had reduced risk for severe symptoms, complications, and death,” the investigators report. “Vaccination coverage among pregnant women remains a priority.”
The large, prospective, observational study included 4,618 pregnant women in 41 hospitals across 18 countries. The study period runs from Nov. 27, 2021, to June 20, 2022, a period when the omicron variant was the dominant strain. Compared with 2 unmatched women without a COVID-19 diagnosis during pregnancy or at delivery, women with laboratory-confirmed COVID-19 had these outcomes based on primary outcomes of maternal morbidity and mortality index (MMMI), severe neonatal morbidity index (SNMI), and severe perinatal morbidity and mortality index (SPMMI): “1,545 (33%) women had a COVID-19 diagnosis (median gestation 36.7 weeks [IQR 29.0–38.9]) and 3,073 (67%) women, with similar demographic characteristics, did not have a COVID-19 diagnosis. Overall, women with a diagnosis had an increased risk for MMMI (relative risk [RR] 1.16 [95% CI 1.03–1.31]) and SPMMI (RR 1.21 [95% CI 1.00–1.46]). Women with a diagnosis, compared with those without a diagnosis, also had increased risks of SNMI (RR 1.23 [95% CI 0.88–1.71]), although the lower bounds of the 95% CI crossed unity. Unvaccinated women with a COVID-19 diagnosis had a greater risk of MMMI (RR 1.36 [95% CI 1.12–1.65]). Severe COVID-19 symptoms in the total sample increased the risk of severe maternal complications (RR 2.51 [95% CI 1.84–3.43]), perinatal complications (RR 1.84 [95% CI 1.02–3.34]), and referral, intensive care unit (ICU) admission, or death (RR 11.83 [95% CI 6.67–20.97]). Severe COVID-19 symptoms in unvaccinated women increased the risk of MMMI (RR 2.88 [95% CI 2.02–4.12]) and referral, ICU admission, or death (RR 20.82 [95% CI 10.44–41.54]). 2,886 (63%) of 4,618 total participants had at least a single dose of any vaccine, and 2,476 (54%) of 4,618 had either complete or booster doses. Vaccine effectiveness (all vaccines combined) for severe complications of COVID-19 for all women with a complete regimen was 48% (95% CI 22–65) and 76% (47–89) after a booster dose. For women with a COVID-19 diagnosis, vaccine effectiveness of all vaccines combined for women with a complete regimen was 74% (95% CI 48–87) and 91% (65–98) after a booster dose.”