Abstract
Background:
SARS-CoV-2 infection is still ongoing worldwide. The passage of SARS-CoV-2 antibodies through human milk provides essential protection to infants. The objective of this study was to determine the presence of immunoglobulins in the human milk at 2 and 6 weeks post-delivery of women who tested positive for the SARS-CoV-2 virus during pregnancy.
Methods:
This prospective observational cohort study was conducted between April 2020 and January 2021. We collected human milk from mothers who tested positive for the SARS-CoV-2 virus during pregnancy. Human milk IgG and IgA antibodies against SARS-CoV-2 S1 RBD protein were measured.
Results:
Eighty-one human milk samples were collected from 57 mothers infected during pregnancy. Human milk collected at 2 weeks post-delivery was positive for SARS-CoV-2 IgG in 82% and IgA in 49% of samples. At 6 weeks, human milk was positive for SARS-CoV-2 IgG in 67% and for IgA in 37% of samples. There was no correlation between the IgG or IgA levels at 2 weeks post-delivery and days from the first positive PCR test to delivery or gestational age at the first positive PCR test. SARS-CoV-2 antibodies were detectable in human milk of mothers who were PCR positive early in gestation. There was no significant difference in human milk IgG or IgA levels when comparing maternal symptom severity. The IgA and IgG levels were lower at 6 weeks compared to 2 weeks in 79% of the paired samples.
Conclusions:
Human milk of mothers infected with the SARS-CoV-2 virus during pregnancy showed the presence of both IgG and IgA against the virus protein. Continued human milk feeding of infants born to mothers infected with SARS-CoV-2 should be encouraged to optimize protective antibodies transferred to the infant.