Study strengths and limitations
To our knowledge, this is the largest series of breast milk samples from
women with SARS-CoV-2 infection during pregnancy or at the time of
delivery. We also collected paired colostrum and mature milk samples
from many women and, for many of them, their serological status at the
time of milk sampling was also recorded, which allowed us to study
correlations between colostrum, mature milk and maternal serological
status. Additionally, the protocol for collection, handling and storage
of samples9 was early defined and implemented in all
centers.
However, the main limitations relate to the small sample size and the
additional technical difficulties that reduced the sample further, which
may have prevented us to recognize any other association or significant
finding.