Abstract
Objective Estimating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence
is an important part of the public health approach to coronavirus disease 2019 (COVID-19)
understanding and containment. This is particularly relevant to an obstetric population
because of implications in the management of the pregnant host, care of the newborn,
and disease progression within the community.
Study Design A cross-sectional seroprevalence study was performed in four Department of Health
Palm Beach County clinics from June 29, 2020, to August 5, 2020. Samples were collected
from asymptomatic antepartum and postpartum participants. A web-based surveillance
system was used to identify subsequent antibody or polymerase chain reaction (PCR)
testing encounters.
Results A total of 163 of 618 subjects were seropositive (26.4%). Racial makeup was white
2.5%, black 19.0%, and Hispanic 78.5%. Positive serology was seen in 16.0, 35.6, and
30.1% of first, second, and third trimesters, respectively; 18.4% were positive postpartum.
Only four patients voluntarily reported PCR positivity prior to antibody testing.
Six home zip codes accounted for the majority (68.1%) of positive results. Thirty-two
patients had repeat serology (65.6% positive and 34.4% negative). Of the 163 subjects,
65 underwent later PCR testing with 92% negative for SAR-CoV-2.
Conclusion Almost one in four subjects had serologic evidence of previous SARS-CoV-2 infection.
These very high seroprevalence rates have not been previously reported and highlight
the concern for health disparities in the United States. Most were asymptomatic and
without a history for SARS-CoV-2 exposure. There was a loss of seropositivity in a
significant number of subjects, raising concern for risk of reinfection, inadequate
transplacental antibody transfer, and subsequent limited passive protection to the
newborn. These seroprevalence data will also allow for better newborn follow-up of
unanticipated consequences of COVID-19 infection in pregnancy.
Key Points
SAR-CoV-2 seroprevalence is disproportionately high in this obstetric population
The majority of subjects who tested positive for SAR-CoV-2 were asymptomatic for COVID-19
infection
Estimating seroprevalence is an important public health approach to disease surveillance
and understanding
Keywords SARS-CoV-2 - epidemiology - pregnancy - seroprevalence
