Rapid antigen detection testing for universal screening for severe acute respiratory syndrome coronavirus 2 in women admitted for delivery

Objective

In the recent year, the rapidly emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has posed major challenges on public health systems.¹ Timely detection of cases is considered crucial to help forestall this unprecedented coronavirus disease 19 (COVID-19) pandemic. This is of utmost importance in the obstetrical population, because these women have multiple interactions with the healthcare systems and with other parturients when admitted for delivery. Hence, universal screening for SARS-CoV-2 was suggested as useful means among women presenting for delivery.² The gold-standard recommended diagnostic method for SARS-CoV-2 is real-time reverse-transcription polymerase chain reaction (RT-PCR).³ Nevertheless, the laboratory capacities to perform RT-PCR in a timely manner in this setting are limited, calling for alternative assays. The introduction of rapid detection tests (RDTs) was suggested as a useful means for earlier detection of positive cases.⁴ We aimed to evaluate the performance of an antigen-based RDT for universal screening for SARS-CoV-2 in women admitted for delivery.

Study Design

A prospective study following asymptomatic women admitted for delivery between October 21, 2020, and December 28, 2020, in a university affiliated hospital in Israel. At the time of admission, nasopharyngeal swabs from all women were collected for universal screening for SARS-CoV-2 using an antigen-based RDT (NowCheck COVID-19 Ag Test, Bionote Inc, Hwaseong-si, Republic of Korea). All women were cotested using the gold-standard RT-PCR on the NeuMoDx 288 Molecular System (NeuMoDx Molecular, Ann Arbor, MI). The institutional review board approved this study.

Results

A total 1326 parturients were included and cotested at their time of admission using both an antigen-based RDT and RT-PCR. Of them, 9 (0.7%) had a positive result for SARS-CoV-2 using RT-PCR. Of the latter, 5 had a positive result using the antigen-based RDT, whereas the other 4 had a negative result (ie, false negative), resulting in a sensitivity of 55.6% (95% confidence interval [CI], 21.2–86.3). Among the 9 women who had a positive result for SARS-CoV-2 using RT-PCR, all those who also had a positive result by the antigen-based RDT had a cycle threshold (Ct) value below 30 (16, 25, 28, 28, 29), whereas the 4 women with a negative antigen-based RDT result had a Ct value equal or higher than 30 (30, 31, 31, 33). None of the women who had a negative result using the RT-PCR had a positive antigen-based RDT result, resulting in a specificity of 100% (95% CI, 99.7–100.0).

Conclusion

The use of point-of-care antigen-based RDT for universal SARS-CoV-2 screening among asymptomatic parturients was shown in this study to have moderate sensitivity and high specificity. The potential benefits of a universal testing approach using RDT among women admitted for delivery may allow timely determination of COVID-19 status that will guide the utilization of proper protection measures and inform neonatal care.