With no end in sight to the convergence of COVID-19, countries are
struggling with strategies to halt the “second wave” and mitigate
economic decline. Estimated to account for around half of the
infections, asymptomatic transmission of SARS-CoV-2 has been hampering
the containment of the virus. A positive case rate of 10% was reported
by Prabhu et al. among 625 pregnant women who were universally screened
for SARS-CoV-2 on the day of admission for delivery at 3 institutions in
New York City, of which 80% were asymptomatic at the time of testing
including pre- and post-symptomatic patients. As evidence shows that
virus sheds before symptoms appear and even after their cessation, these
populations may have increased the chances of COVID-19 outbreak in the
hospitals. Utilization of testing results for isolation practices was
not mentioned in the report, possibly given the long turnaround time for
the testing platforms at the time.
While the risk of nosocomial transmission is affected by clinical
settings, the intimate and prolonged nature of childbirth elevates the
risk of cross-infection between midwives and women. The role of
nosocomial transmission has been increasingly recognized, and its
severity risk may be greater than those of community-acquired
infections. A recent report has suggested facilities to consider testing
pregnant women for SARS-CoV-2 at the time of admission (Rasmussen SA, et
al. JAMA. 2020). International Confederation of Midwives has also called
for governments to prioritize testing for all pregnant women and their
care providers. Identification of infectious women prior to delivery
could contribute to prevention of further transmission to patients and
healthcare workers. Importance should also be emphasized on evaluating
contact history due to the nature of false-negative PCR results
(Woloshin S, et al. NEJM. 2020).
Another significance of performing testing for SARS-CoV-2 on pregnant
women is for the adequate medical management of the women and the
fetuses. While outcome for mothers and neonates seems generally
favorable, data suggest that pregnancy can be associated with increased
risk for severity, including intensive care unit admission and receipt
of mechanical ventilation (Ellington S, et al., MMWR Morb Mortal Wkly
Rep 2020;69:769–775). Furthermore, a recent article has raised concerns
over transplacental transmission of SARS-CoV-2 to the fetus (Vivanti AJ,
et al. Nat Commun. 2020;11:3572). Collection of longitudinal data is
crucial to understand the effects of SARS-CoV-2 infection on maternal
and neonatal outcomes. Results of large-scale prospective cohort
studies, such as INTERCOVID study, are expected to add high-quality
evidence on the effects of COVID-19 in pregnancy on the health of the
mothers, fetuses, and newborns.
Screening a maternity population under a pandemic can be a way to
provide a glimpse of the distribution of the population, since capacity
constraints still impede widespread testing in many countries. Recent
development of faster diagnostic testing could bring improvement, but
test sensitivity will remain a challenge. Fundamental preventive
measures and clinical management should be continued; that is, hygiene
and social distancing practices for women themselves, and careful
evaluation of each mother and fetus for care providers.