Human Milk Antibodies after BNT162b2 Vaccination Exhibit Reduced Binding against SARS-CoV-2 Variants of Concern.

Jia Ming Low,Zubair Amin,Melissa Shu Feng Ng,Youjia Zhong,Yue Gu,Paul A. MacAry,Liang Wei Wang

doi:10.3390/vaccines10020225

Abstract

SARS-CoV-2-specific antibody responses are engendered in human milk after BNT162b2 vaccination. However, the emergence of variants of concern (VOCs) raises concerns about the specificity of and potential cross-protection mediated by milk antibody responses, which are crucial for passive immunity transferred from breastfeeding mothers to their infants. In this study, we collected milk samples at three different time points pre- and post-vaccination, and measured milk IgA antibody binding to the receptor binding domain (RBD) of the original Wuhan-Hu-1 strain, and the four VOCs, namely Alpha, Beta, Gamma and Delta. We report a significant level of anti-RBD IgA in milk collected at 4–6 weeks after the second dose of vaccination compared to pre-vaccination. We observed around a 30% reduction in binding to most VOCs, including the major circulating Delta variant, compared to the original Wuhan-Hu-1 strain. As COVID-19 vaccines may take some time to be approved for infants, these individuals remain at risk for severe disease and rely mainly on transferred passive immunity. Our findings support the current recommendations for vaccinating lactating women with the aim of transferring mucosal immunity to breastfeeding infants.

Highlights

SARS-CoV-2-specific antibody responses are engendered in human milk after vaccination with Pfizer/BioNTech’s BNT162b2 [1], as well as Moderna’s mRNA-1273 [2]
Over the course of the pandemic, numerous variants have arisen, numbering nine as of December 2021 [3]. While some of these variants are of minimal clinical concern and are deemed as variants of interest, World Health Organization (WHO)-designated variants of concern (VOCs) have increased potential for spread and may cause more severe disease
Given that existing vaccines, including BNT162b2, utilize earlier virus strains for their design, questions have been raised regarding the specificity and potential cross-protection mediated by these antibodies

Summary

Introduction

SARS-CoV-2-specific antibody responses are engendered in human milk after vaccination with Pfizer/BioNTech’s BNT162b2 ( known as Comirnaty; INN: tozinameran) [1], as well as Moderna’s mRNA-1273 [2]. Both of these mRNA vaccines encode a humancodon-optimized SARS-CoV-2 spike glycoprotein, using the first described Wuhan-Hu-1 strain as the basis for design, together with proline substitutions at lysine and valine to stabilize the prefusion intermediate. Over the course of the pandemic, numerous variants have arisen, numbering nine as of December 2021 [3] While some of these variants are of minimal clinical concern and are deemed as variants of interest, World Health Organization (WHO)-designated variants of concern (VOCs) have increased potential for spread and may cause more severe disease. Further studies on milk antibodies generated to the COVID-19 vaccines are warranted

Methods

Discussion

Conclusion