Effect of SARS-CoV-2 vaccine on the breastmilk antibody response among lactating healthcare workers

Abstract

Abstract In 2019, a deadly virus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for COVID-19, emerged. Two mRNA-based COVID-19 vaccines were approved for use in December 2020 in the US and have begun providing immunity to those receiving the vaccination. Certain vaccines given to pregnant and lactating mothers provide immunity to infants through transmission across the placenta and umbilical cord (IgG) and breast milk (IgA). Breastmilk produced by mothers with a history of COVID-19 infection has found to be a source of anti-SARS-CoV-2 IgA and IgG. This study aimed to determine the presence of specific SARS-CoV-2 IgA in the breastmilk of lactating women after the COVID-19 vaccine administration. As such, lactating healthcare workers who received the SARS-CoV-2 mRNA vaccine (Pfizer-BioNtech or Moderna) made up a sample group. Plasma and breast milk were collected at three time points (pre-vaccination, 14–28 days post first dose of vaccine, and 7 days post second dose of vaccine). SARS-CoV-2 specific IgA (breastmilk) and IgG (plasma) concentration were then measured by ELISA. We found consistent secretion of SARS-CoV-2 specific IgA in breast milk after COVID-19 vaccination. The second dose of the SARS-CoV-2 vaccine was necessary to elicit IgA response in breastmilk detectable by ELISA. There is a correlation of the level of SARS-CoV-2 specific IgG in blood with SARS-CoV-2 specific IgA in breastmilk. Our results show that the mRNA-based COVID-19 vaccines from Pfizer-BioNTech and Moderna induce SARS-CoV-2 specific IgA secretion in breastmilk. Further studies are needed to determine the duration of this immune response and a possible passive immunity transfer of SARS-CoV-2 specific IgA to breastfeeding infants.