key: cord-0800451-ewkzmx71
authors: LaCourse, Sylvia M; Kachikis, Alisa; Blain, Michela; Simmons, LaVone E; Mays, James A; Pattison, Amber D; Salerno, Carol C; McCartney, Stephen A; Kretzer, Nicole M; Resnick, Rebecca; Shay, Rosemary L; Savitsky, Leah M; Curtin, Anna C; Huebner, Emily M; Ma, Kimberly K; Delaney, Shani; Delgado, Carlos; Schippers, Adrienne; Munson, Jeff; Pottinger, Paul S; Cohen, Seth; Neme, Santiago; Bourassa, Lori; Bryan, Andrew; Greninger, Alex; Jerome, Keith R; Roxby, Alison C; Lokken, Erica; Cheng, Edith; Adams Waldorf, Kristina M; Hitti, Jane
title: Low prevalence of SARS-CoV-2 among pregnant and postpartum patients with universal screening in Seattle, Washington
date: 2020-05-30
journal: Clin Infect Dis
DOI: 10.1093/cid/ciaa675
sha: 1deb68a39669711b96306014f33162b1d81adb8f
doc_id: 800451
cord_uid: ewkzmx71

We found a low prevalence of SARS-CoV-2 (2.7% [5/188]) among pregnant and postpartum patients after initiating universal testing. Prevalence among symptomatic patients (22.2% [4/18]) was similar to initial targeted screening approaches (19.1% [8/42]). Among 170 asymptomatic patients, two were positive or inconclusive, respectively; repeat testing at 24 hours was negative.

To date, most COVID-19 reports in pregnancy are case series, with limited insight into population prevalence [1] [2] [3] [4] [5] . Reports from New York City described an alarming rate of asymptomatic SARS-CoV-2 PCR-positive pregnant patients (13.7-14.5%) [6, 7] . Although Washington State was among the first to confirm community transmission [8] , our regional epidemic appears to be slowing with early public health response and widespread testing availability [9] . On March 2, 2020, University of Washington (UW) Department of Laboratory Medicine obtained Emergency Use Authorization (EUA) for a laboratory-developed SARS-CoV-2 test. Initial testing at UW Medicine focused on symptomatic persons under investigation (PUI), transitioning to universal testing of labor and delivery (L&D) and

pre-surgical patients March 29, 2020. We present results of L&D SARS-CoV-2 PCR testing March 2, 2020-April 15, 2020, encompassing targeted and universal approaches.

We performed a retrospective cohort study of SARS-CoV-2 PCR testing of L&D patients at UW 

Routine centralized UW Virology Laboratory testing utilized one of three RT-PCR assays depending 

Patient and testing characteristics were summarized by proportions and medians with interquartile range (IQR) as appropriate. Testing results were characterized as positive, negative, or inconclusive. M a n u s c r i p t 6

Between March 2, 2020-April 15, 2020, 230 pregnant and postpartum patients underwent SARS-CoV-2 testing; 42 (18.3%) under the initial targeted symptomatic PUI approach, and 188 (81.7%) under universal testing (Figure) .

Supplemental Table 1 

SARS-CoV-2 prevalence among symptomatic patients during initial targeted PUI screening (19.1% Thirty patients (13%) underwent repeat testing with 45 additional tests performed (Supplemental Table 2 ). Additional testing indication included: 6 (13.3%) symptomatic PUI (with negative results), 19 (42.2%) known SARS-CoV-2 positive, 2 (4.3%) previously inconclusive, and 18 (40.0%) for universal screening of asymptomatic patients. Nine patients with initial positive tests underwent retesting;

A c c e p t e d M a n u s c r i p t 7 seven had at least one additional positive test, including six initially symptomatic patients who remained PCR-positive for >2 weeks (Figure 1) . No patient with an initial negative or inconclusive test subsequently tested positive.

Among 275 total tests performed, 193 (70.2%) were tested by routine and 82 (29.8%) by rapid test.

Median turn-around time was 2.5 hours (IQR 2.0-3.1) for rapid, and 7.1 hours (IQR 5.5-9.3) for routine tests (aggregate data reported; disaggregated initial and repeat testing reported in Supplemental Table 1 , 2).

We found low prevalence of SARS-CoV-2 among L&D patients after initiating universal screening.

Universal testing was accomplished using a combination of on-site rapid testing, high throughput centralized testing, and outpatient drive-through screening prior to admission. This multipronged approach ensured almost all patients had a known SARS-CoV-2 status prior to delivery or procedure, including patients with precipitous labor or requiring emergent/urgent procedures. Among a small subset of PCR-positive patients retested, a high proportion remained positive for >2 weeks. While rapid testing aided in short turn-around times, routine testing provided results within 8 hours, further improved to ~6 hours by study end as laboratory capacity increased. This approach was feasible and yielded valuable real-time data on SARS-CoV-2 status enabling judicious PPE use.

Our study has some similar features to recent reports from New York including universal screening of all L&D patients [6, 7] , however, prevalence of confirmed SARS-Cov-2 among both symptomatic and asymptomatic patients differed substantially. The positive rate for symptomatic PUI screening in our study was 19.1-22.2%, in contrast to reported rates of 68.8% (11/16) and 100% (4/4) in New York [6, 7] . Only 1.2% of asymptomatic women tested positive or inconclusive for SARS-CoV-2 in our study, compared to 13.7-14.5% in New York reports, and neither patient was positive upon retesting at 24 hours. Our lower SARS-CoV-2 prevalence among pregnant and postpartum patients likely reflects local epidemic dynamics including potentially earlier community spread, but currently lower A c c e p t e d M a n u s c r i p t 8 prevalence within our region. We estimate the average population prevalence in greater Seattle and King County between March 23 and April 9, 2020 was 0.24% [95% CI 0.05% -0.75%], with evidence of continued decline [9] . Table 2 .Panel B: Results of repeat SARS Co-V-2 testing among initially positive pregnant patients. Timing denotes first and last test performed during the study period by either gestational age (GA) or postpartum (PP) age.

Maternal and neonatal outcomes of pregnant women with COVID-19 pneumonia: a case-control study

Clinical features and obstetric and neonatal outcomes of pregnant patients with COVID-19 in Wuhan, China: a retrospective, single-centre, descriptive study

COVID-19 infection among asymptomatic and symptomatic pregnant women: Two weeks of confirmed presentations to an affiliated pair of New York City hospitals

Clinical Characteristics of Pregnant Women with Covid-19 in Wuhan, China

Maternal and Perinatal Outcomes with COVID-19: a systematic review of 108 pregnancies

Screening all pregnant women admitted to Labor and Delivery for the virus responsible for COVID-19

Universal Screening for SARS-CoV-2 in Women Admitted for Delivery

First Case of 2019 Novel Coronavirus in the United States

Greater Seattle Coronavirus Assessment Network (SCAN)

M a n u s c r i p t 9 benefits of infant separation/co-location and breastfeeding practices, utilizing a shared-decision making approach. Despite low numbers of additional cases identified, universal screening of pregnant patients provides important surveillance information due to the representativeness of this population to the greater community.