Anti-Sars-Cov-2 IgA And IgG In Human Milk After Vaccination Is Dependent On Vaccine Type And Previous Sars-Cov-2 Exposure: A Longitudinal Study
Authors: Selma-Royo Marta , Bäuerl Christine , Mena-Tudela Desirée , Aguilar-Camprubí Laia , Pérez-Cano Francisco J , Parra-Llorca Anna , Lerin Carles , Martínez-Costa Cecilia , Collado Maria Carmen 
Published: May 2021

Structured AbstractImportanceLimited data are available on COVID-19 vaccine impact in lactating women.ObjectiveTo evaluate the impact of different COVID-19 vaccines on specific anti-SARS-CoV-2 IgA and IgG levels in human milk.Design, Settings and ParticipantsIn this prospective observational study in Spain, 75 lactating women from priority groups receiving vaccination against SARS-CoV-2 were included (January to April 2021). Human milk samples were collected at seven-time points. A group with confirmed SARS-CoV-2 infection (n=19) and a group of women from prepandemic time (n=13) were included.ExposuremRNA vaccines (BNT162b2 and mRNA-1273) and adenovirus-vectored vaccine (ChAdOx1 nCoV-19).Main Outcome(s) and Measure(s)Presence of IgA and IgG against RBD SARS-CoV-2 in breast milk.ResultsSeventy-five vaccinated lactating women [mean age, 34.9 ± 3.7 years] of whom 96% were Caucasic and 92% were health care workers. A total of 417 milk samples were included and vaccine distribution was BioNTech/Pfizer (BNT162b2, n=30), Moderna (mRNA-1273, n=21), and AstraZeneca (ChAdOx1 nCoV-19, n=24). For each vaccine, 7 time points were collected from baseline up to 25 days after the 1st dose and same points were collected for mRNA vaccines 30 days after 2nd dose. A strong reactivity was observed for IgG and IgA after vaccination mainly after the 2nd dose. Presence and the persistence of specific SARS-CoV-2 antibodies in breast milk were dependent on the vaccine-type and, on previous virus exposure. High inter-variability was observed, being relevant for IgA antibodies. IgG levels were significantly higher than those observed in milk from COVID-19 women while IgA levels were lower. Women with previous COVID-19 increased the IgG levels after the 1st dose to a similar level observed in vaccinated women after the 2nd dose.Conclusions and RelevanceBreast milk from vaccinated women contains anti-SARS-CoV-2 IgA and IgG, with highest after the 2nd dose. Levels were dependent on vaccine type and previous exposure to SARS-CoV-2. Previous COVID-19 influenced the vaccine effect after a single dose, which could be especially relevant in the design of vaccination protocols. Further studies are warranted to demonstrate the potential protective role of these antibodies against COVID-19 in infants from vaccinated and infected mothers through breastfeeding.Trial RegistrationNCT04751734Key PointsQuestionWhat is the effect of the different COVID-19 vaccines on the anti-SARS-CoV-2 antibodies in breast milk? Is the vaccine-specific antibody response in milk comparable to a natural infection? What would be the effect of vaccination on human milk antibodies in women with past SARS-CoV-2 infection?FindingsIn this prospective, observational and multicenter study in Spain, lactating women within the priority groups receiving the vaccination against SARS-CoV-2 were included. Although there is a high intra- and inter-variability in the generation of specific SARS-CoV-2 antibodies in breast milk, they are also dependent on the vaccine-type and previous viral exposure.MeaningMaternal SARS-CoV-2 vaccination provides anti-SARS-CoV-2 antibodies, both IgA and IgG, in human milk and it depends on vaccines and previous COVID-19.