SARS-CoV-2 Infection Rate 16% in Asymptomatic Pregnant Women at Delivery

Jake Remaly

May 29, 2020

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Among women with a planned delivery in a New York City health system during the first half of April, the rate of asymptomatic SARS-CoV-2 infection was 16%, according to a study published in Obstetrics & Gynecology. Among the patients' designated support persons, the asymptomatic carrier rate was 10%.

"If universal testing of pregnant patients in a high prevalence area is not performed, health care workers will be inadvertently exposed to COVID-19, unless universal precautions with personal protective equipment are taken," wrote the researchers affiliated with the department of obstetrics, gynecology, and reproductive medicine at Icahn School of Medicine at Mount Sinai, New York.

Angela Bianco, MD, and colleagues conducted an observational study of women who were scheduled for a planned delivery within the Mount Sinai Health System between April 4 and April 15, 2020. Patients and their designated support person completed a telephone screen and underwent COVID-19 testing the day before a scheduled delivery. If support persons screened positive during the telephone interview about COVID-19 symptoms, they could not attend the birth, and patients could contact a different support person to be screened and tested. "All patients and their support persons were informed of their SARS-CoV-2 test results before admission," the investigators wrote. "Those who tested positive were counseled regarding symptomatology that should prompt medical attention."

In all, researchers screened 158 patients with a planned delivery, and 155 agreed to undergo COVID-19 testing. Of the 155 women tested, 24 (16%) tested positive for SARS CoV-2 infection. Among 146 support persons who had a negative interview screen and underwent SARS-CoV-2 testing, 14 (10%) tested positive for SARS-CoV-2 infection.

Test results were substantially concordant among patient and support person pairs. "Among patients who tested positive for COVID-19 infection and had a support person present, 11 of 19 (58%) support persons also tested positive for COVID-19 infection," the authors reported. "Among patients who tested negative for COVID-19 infection and had a support person present, only 3 of 127 (2.4%) support persons tested positive for COVID-19 infection."

Telephone screening did not identify any of the COVID-19–positive cases. Of the 24 patients with SARS-CoV-2 infection, none of their newborns tested positive at birth.

"Universal testing ... provides a mechanism for more accurate counseling of patients regarding issues such as newborn skin-to-skin contact and breastfeeding," noted Dr. Bianco and colleagues. At their institution, parents with COVID-19 are instructed to wear a mask and practice proper hand hygiene when caring for their newborns.

Kristina Adams Waldorf, MD, said in an interview that the study by Bianco et al. underscores the high rate of asymptomatic or mildly symptomatic COVID-19 infections detected with universal screening in a hospital at the U.S. epicenter of the pandemic. "Each state and hospital will need to evaluate their own data to determine the value of universal screening for their patient population. In rural parts of America that have yet to see cases, universal screening may not make sense, but these areas are likely to be few and far between. The rest of America will need to quickly get on board with universal screening to protect their labor and delivery staff."

Testing the partner was a strength of the study. "It is reassuring that when a pregnant woman tested negative for SARS-CoV-2, the rate was very, very low (2.4%) that her partner would test positive. However, it was disconcerting that telephone screening for common symptoms associated with COVID-19 was not very helpful in identifying cases," said Dr. Waldorf, a professor of obstetrics and gynecology at the University of Washington, Seattle. She was not involved in the study by Bianco et al.

One study author receives payment from the American Board of Obstetrics and Gynecology for serving as a board examiner, receives payment from UpToDate, and serves as an expert witness in malpractice and products liability cases. The other authors did not report any potential conflicts of interest. Dr. Waldorf said she had no relevant financial disclosures.

SOURCE: Bianco A et al. Obstet Gynecol. 2020 May 19. doi: 10.1097/AOG.0000000000003985.

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