key: cord-0782578-av7sk3ac
authors: Mo, Huaheng; Wang, Ming; Wang, Mengmei; Han, Yi; Zhang, Yingying; Hu, Ke
title: Detectable antibodies against SARS-CoV-2 in newborns from mothers infected with COVID-19 at different gestational ages
date: 2021-03-26
journal: Pediatr Neonatol
DOI: 10.1016/j.pedneo.2021.03.011
sha: 8d0c6261e8cf2b8e33d17d28ba69dbf1f35db83a
doc_id: 782578
cord_uid: av7sk3ac

nan

Detectable antibodies against severe acute respiratory syndrome coronavirus 2 in newborns from mothers infected with corona virus disease-2019 at different gestational ages

Maternal antibodies may partially confer protection to neonates from some viral infections [1] ; however, understanding the nature and durability of perinatal humoral immune responses to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is limited [2] . In this study, dynamic changes of antibody levels of six newborns born to mothers with corona virus disease-2019 (COVID-19) were investigated.

Out of six pregnant women with laboratory-confirmed COVID-19, three were in the second trimester of pregnancy, with gestational ages of 28 weeks and 4 days, 29 weeks and 5 days, and 17 weeks and 5 days, and the other three were in the third trimester of pregnancy, with gestational ages of 36 weeks and 1 day, 37 weeks and 2 days, and 34 weeks and 1 day. Throat swab and blood samples were collected from all pregnant women at delivery and from their newborns at birth. After delivery, all six mothers with their newborns were followed-up for six months and were re-tested for viral nucleic acid and serum antibodies every month (±1 week). Antibody testing was conducted using qualitative (colloidal gold) antibody-detection kits or quantitative chemiluminescence immunoassay. Levels of IgG and IgM antibody are shown in Table 1 . All women in the third trimester of pregnancy had detectable levels of specific IgM and IgG at delivery, and their newborns at birth had apparent IgG and one had IgM. After delivery, one mother had detectable IgM for 60 days, another for 90 days, and the third had it <30 days.

However, those three mothers had recognizable IgG for four or five months. Of their three newborns, two had duration of detectable IgG of 120 days and one had duration of 60 days. One had duration of IgM above 10 AU/mL for 30 days. Upon delivery, three infected women in the second trimester with their newborns were asymptomatic having negative PCR results; however, were positive for IgG but negative for IgM.

Six months later, these mothers still had high titers of IgG reaching a >4-fold increase above the cut-off value. Detectable levels of IgG in three newborns lasted for 150, 180, and 180 days, respectively.

In this study, levels of SARS-CoV-2 specific antibodies in infants from mothers infected with COVID-19 at different gestational ages were monitored. Of six pregnant infected women in January, 2020, three were in their third trimester and the other three at their second trimester. However, they had different responses of immunity. Maternal antibodies may protect the fetus from maternal in utero transmission [1] . However, antibody persistence in infants born to infected women with COVID-19 is very unclear. Thus, this study focused on the potential duration of neonatal antibody IgG. Regarding the duration of passive immunity from gestational maternal SARS-CoV-2 specific IgG in neonates, our findings are in agreement with published results [2, 3, 4] . These results also demonstrated that asymptomatic infants had a strong immune response from their COVID-19 mothers infected in the second trimester of pregnancy. This may be related to the characteristics of antibodies, since IgG may be passively transferred from the mother to the fetus through the placenta, which begins at the end of the second trimester and reaches high levels at the time of birth [5] . Maternal IgM usually does not pass through an intact placental barrier due to its larger macromolecular structure.

Our data might have implications for understanding the duration of protective effect from maternal to infants, and for potential vaccination efforts. However, more work is needed to understand SARS-CoV-2 immunity in infants, because it is unclear what level of antibody titers in infants are considered protective against infection [6] . 

Maternal immunization

Humoral immune response to SARS-CoV-2 in Iceland

Disappearance of SARS-CoV-2 antibodies in infants born to women with COVID-19

Dynamic changes in anti-SARS-CoV-2 antibodies during SARS-CoV-2 infection and recovery from COVID-19

Elevation of cord over maternal IgG immunoglobulin: evidence for an active placental IgG transport

The power of antibody-based surveillance

This work was supported by the National Key Research and Development Plan

Apgar score (1 min, 5 min, 10 min) 9, 10, 10 9, 10, 10 9, 10, 10 9, 10, 10 9, 10, 10 9, 10, 10