This will be a prospective observational study of lactating mothers who are planning to,have scheduled or have received vaccination against SARS-COV-2 (COVID-19 vaccine).Mothers may have delivered at Mount Sinai Hospital or may be from the general publicrecruited by social media or word of mouth. As the study participants will be lactatingmothers, they will not be under the care of the investigators. Due to lack ofinformation, we are unsure of an appropriate sample size but envision we will recruit atleast 10 women each immunized with the approved mRNA vaccines (e.g. Pfizer-BioNTech andModerna COVID-19 vaccines) and in the future at least two other vaccines (e.g.Oxford-AstraZeneca) as they are approved and become available. Milk samples will beanalyzed for the presence of antibody to SARS-CoV-2 using the Anti-SARS-CoV-2 ELISA (IgGand IgA). These analyses will be conducted in the Department of Microbiology at SinaiHealth following validation of the procedures in human milk.