key: cord-0769837-p9l7sqlj
authors: Schwartz, Anat; Nir, Omer; Toussia-Cohen, Shlomi; Leibovich, Leah; Strauss, Tzipora; Asraf, Keren; Doolman, Ram; Sharabi, Sivan; Cohen, Carmit; Sapir, Einav; Lustig, Yaniv; Regev-Yochay, Gili; Yinon, Yoav
title: Presence of SARS-CoV-2 antibodies in lactating women and their infants following BNT162b2mRNA vaccine
date: 2021-08-02
journal: Am J Obstet Gynecol
DOI: 10.1016/j.ajog.2021.07.016
sha: 7ade75a80d3e70c29eb6be2fb19c32f0c2cebe53
doc_id: 769837
cord_uid: p9l7sqlj

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Pregnant and lactating women were excluded from initial clinical trials evaluating the safety and 33 efficacy of BNT6b2 mRNA vaccine. Consequently, recommendations regarding their 34 vaccination were equivocal. 1 Therefore, our aim was to assess whether SARS-CoV-2 immunoglobulins 35 can be detected in breastmilk samples following COVID-19 vaccination of lactating women and in their 36 infant's serum and oral mucosa secretions. 37

A longitudinal cohort study between December 2020 and April 2021. Lactating women 39 who were vaccinated against COVID-19 after delivery and their infants were sampled. Blood 40 samples and breastmilk were obtained from all study participants, and dried bloods spots (DBS) 41 samples from infants of the breastfeeding mothers were also collected on Guthrie cards.

Additionally, infant's saliva was collected from oral mucosa immediately after breastfeeding, as 43 well as 30, 90 and 150 minutes afterwards. All serum samples were tested for SARS-CoV-2 IgG.

DBS and milk samples were tested for SARS-CoV-2 IgG and IgA by a Receptor-Binding-Domain 45 ELISA Samples cutoff (S/Co) equal or above 1.1 were considered positive.

Additionally, neutralization assay was performed on milk samples using a green fluorescent protein 47

reporter-based pseudo-typed virus with a vesicular stomatitis virus backbone coated with SARS-CoV-2 48 spike (S) protein. Sera not capable of reducing viral replication by 50% at 1 to 8 dilutions were 49 considered non-neutralizing. 50

Women who were diagnosed with COVID-19 infection and/ or were vaccinated before birth were 51 excluded.

Maternal sera and breast milk samples were obtained from 61 participated women. All maternal sera, as 54 well as breastmilk samples, were positive for SARS-CoV-2 IgG with a median concentration of 31.7 55 (IQR 25.1-38.1) S/Co, and 6.3 (IQR 5.1-7.4) S/Co, respectively. There was a significant positive 56 correlation between maternal serum levels and breastmilk levels of SARS-CoV-2 IgG (r = 0.514, P = 57 0.0001). Moreover, as depicted in figure 1 , eighteen of 47 milk samples (38.3%) were found to neutralize 58 SARS-CoV-2 infectivity. SARS-CoV-2 IgG was detected in the oral mucosa of three of five (60%) 59 breastfed infants. However, all of the 21 infants' DBS sampled who were obtained were negative for 60 these antibodies. 61 SARS-CoV-2 IgA in secretory form (sIgA) was detected in 15% of the breastmilk samples, with a median 62 of 0.4 S/Co (IQR 0.3-0.7). 63

In this longitudinal cohort study, lactating women vaccinated to COVID-19 were found to have SARS- 

Vaccinating Pregnant and Lactating Patients Against COVID-19. ACOG Practice Advisory

COVID-19 83 vaccine response in pregnant and lactating women: a cohort study

Antibodies in Breast Milk After COVID-19 Vaccination of Breastfeeding Women

Anti-SARS-CoV-2 antibodies induced in 89 breast milk after Pfizer-BioNTech/BNT162b2 vaccination

Antibody Response to Coronavirus Disease 2019 ( 91 COVID-19 ) Messenger RNA Vaccination in Pregnant Women and Transplacental Passage Into 92 Cord Blood