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Delta variant increases COVID-19 risks for pregnant women

Compared to coronavirus cases earlier in the pandemic, infections with the Delta variant lead to worse outcomes for unvaccinated pregnant women, new data suggest.

Doctors studied 1,515 pregnant women with COVID-19 who received care from a large public health system in Dallas from May 2020 to 4 September 2021. Overall, 82 women, 81 of whom were unvaccinated, developed severe illness, including 10 who needed ventilators and two who died.

The proportion of severe or critical cases among pregnant women was around 5% until early 2021, and “largely non-existent” in February and most of March 2021, the researchers said in a statement. In late summer, during the peak of the surge of the Delta variant, the proportion of pregnant COVID-19 patients requiring hospitalisation jumped to 10% to 15%, they reported in the American Journal of Obstetrics and Gynaecology.

Pregnant women face greater risks for complications with any type of severe respiratory infection, so these findings of the higher risk from the Delta variant further emphasise the need for them to get vaccinated for COVID-19, said study leader Dr Emily Adhikari of the University of Texas Southwestern Medical Center.

On Wednesday, adds Reuters, the US Centers for Disease Control and Prevention called for “urgent action” to increase COVID-19 vaccination among pregnant women, recently pregnant, including those who are breastfeeding, or who might become pregnant in the future, saying “the benefits of vaccination outweigh known or potential risks”.

Study details

Increasing severity of COVID-19 in pregnancy with Delta (B.1.617.2) variant surge
Emily Adhikari, Jeffrey SoRelle, Donald McIntire, Catherine Spong,

Published in American Journal of Gynecology on 13 September 2021

Objective
The Delta (B.1.617.2) variant of the SARS-CoV-2 virus became the predominant variant circulating in the United States beginning July 2021. We report the trends of illness severity among obstetrical patients with COVID-19, on a background of Delta variant predominance and describe COVID-19 vaccinations in this cohort at Parkland Hospital—a public county hospital.

Study Design
We prospectively studied pregnant patients diagnosed with SARS-CoV-2 by nasal or nasopharyngeal swab polymerase chain reaction, in a large prenatal system encompassing a centralised acute care hospital and 10 community-based prenatal clinics, all with an integrated electronic health record. Externally tested patients who received care at Parkland were also included. In mid-May 2020, universal SARS-COV-2 screening was implemented for obstetrical patients on hospital admission, with symptom-based testing at outpatient clinics and the emergency department.

Positive tests were grouped into weekly epochs by the date of diagnosis and the maximum severity of symptoms. Severe or critical illness was defined as that requiring supplemental oxygen, a high-flow nasal cannula, intensive care unit admission, or mechanical ventilation. The management of asymptomatic or mild-to-moderate illness in pregnancy included symptom treatment with isolation precautions and virtual or in-person follow-up. The routine management of severe or critical illness included the administration of dexamethasone or other therapies according to the National Institutes of Health guidance.

The association between severe or critical illness and the week was evaluated for the trend using the Mantel-Haenszel chi-squared test for trend. Local SARS-CoV-2 Delta variant (B.1.617.2) sequencing was performed and the variant predominance was tracked weekly. The COVID-19 vaccines were offered from December 2020 onward and the vaccination rates in pregnancy or immediately after childbirth are described.

Results
From May 17, 2020 to September 4, 2021, 1515 pregnant patients were diagnosed with COVID-19, and 7 (0.5%) had reinfection >90 days after the initial infection during pregnancy. The infections included 690 (45%) patients from labour and delivery or inpatient units, 383 (25%) outpatient, 167 (11%) emergency department, and 282 (19%) external tests. Furthermore, 82 (5.4%) cases with severe or critical illness during pregnancy, with 11 (0.7%) requiring mechanical ventilation, 2 (0.1%) maternal deaths whose neonates survived, and 2 (0.1%) foetal-neonatal deaths associated with maternal critical illness, were included.

The proportion of pregnant patients with severe to critical illness increased in April 2021; the total number of cases, however, remained low. As the Delta (B.1.617.2) variant predominated locally, both the case volume and the proportion of severe or critical illnesses increased significantly (P=.001 for trend), with more than a quarter of pregnant patients who were diagnosed between 29 August 2021 and 4 September 2021 requiring admission for severe or critical illness.

Vaccination with any of the COVID-19 vaccines authorised for emergency use was examined in this cohort. Among 665 still pregnant patients or those who had just given birth when the vaccines were available, 142 (21.4%) received at least 1 dose of an available vaccine, including 39 before infection, 99 after infection, and 4 administered between repeat infections. One infected patient was hospitalised for severe COVID-19 after being vaccinated; this patient had a body mass index of 61 kg/m2.

Conclusion
Increased morbidity was observed in pregnancy with COVID-19 during the recent surge associated with the Delta variant, particularly in an underserved pregnant population where vaccine acceptance is low. The overall rates of severe or critical illness in this cohort are consistent with the previously published data from our institution.

However, recent trends demonstrate that along with increasing case volume, the proportion of cases requiring hospitalisation is rising. The potential pathophysiologic mechanisms for the increased severity of illness with B.1.617.2 in pregnancy are unclear. Our results highlight the urgency of the requirement of prevention measures including COVID-19 vaccination during pregnancy.

 

Reuters article – Delta increases COVID-19 risks for pregnant women (Open access)

 

AJOG article – Increasing severity of COVID-19 in pregnancy with Delta (B.1.617.2) variant surge (Open access)

 

See more from MedicalBrief archives:

 

Effectiveness of Pfizer vaccine in pregnancy — Clalit Health Services study

 

Pregnant women pass COVID antibodies to their babies — Weill Cornell

 

Mortality 20x higher in pregnant women with COVID but SAHPRA says no to vaccination

 

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