Relationship between anti-SARS-CoV-2-specific antibodies in human breast
milk following SARS-CoV-2 infection during pregnancy: a prospective
Objective: To determine the presence of anti-SARS-CoV-2 antibodies in
colostrum and mature milk in women who had SARS-CoV-2 infection during
pregnancy or at delivery; to investigate the correlation between
anti-SARS-CoV-2 antibodies in milk with antibody in maternal blood,
severity of infection and time-interval from active illness; and to
evaluate immunoglobulin evolution from colostrum to mature milk. Design:
prospective cohort-study Setting: six hospitals in Spain and Hong-Kong.
Sample: pregnant women with confirmed SARS-CoV-2 infection during
pregnancy or at delivery. Methods: Colostrum and mature milk were
collected by manual expression with strict contact precautions.
Colostrum samples were tested with rRT-PCR-SARS-CoV-2 and both, maternal
milk and serum were tested against SARS-CoV-2 specific immunoglobulin M,
A and G reactive to receptor binding domain of SARS-CoV-2 spike
protein-1. Results: All rRT-PCR-SARS-CoV-2 tested negative. IgA and IgG
were present in 111/135 (82.2%) and 2/135 (1.5%) colostrum samples and
27/81 (33.3%) and 0/81 mature milk samples, respectively.
Concentrations of immunoglobulins were not associated with the timing of
infection but women with SARS-CoV-2 pneumonia had higher levels of IgA
and IgG in colostrum than those who were asymptomatic or had mild
symptoms. Conclusion: No SARS-CoV-2 virus was found in human milk,
however, high levels of antibodies were found in colostrum, specially
IgA, irrespective of the time of infection. All women should be
encouraged to breastfeed, undertaking strict contact precautions when
there is active disease. Funding: Spanish Government grant (Instituto de
Salud Carlos III: COV20/00188). Synlab Diagnostics’ Globales (Madrid,
Spain). Perkin Elmer.