Assessment of SARS-CoV-2 neutralizing antibody titers in breastmilk from convalescent and vaccinated mothers.

Breastmilk contains antibodies that could protect breastfed infants from infections. In this work, we examined if antibodies in breastmilk could neutralize SARS-CoV-2 in 84 breastmilk samples from women that were either vaccinated (Comirnaty, mRNA-1273, or ChAdOx1), infected with SARS-CoV-2, or both infected and vaccinated. The neutralization capacity of these sera was tested using pseudotyped vesicular stomatitis virus carrying either the Wuhan-Hu-1, Delta, or BA.1 Omicron spike proteins. We found that natural infection resulted in higher neutralizing titers and that neutralization correlated positively with levels of immunoglobulin A in breastmilk. In addition, significant differences in the capacity to produce neutralizing antibodies were observed between both mRNA-based vaccines and the adenovirus-vectored ChAdOx1 COVID-19 vaccine. Overall, our results indicate that breastmilk from naturally infected women or those vaccinated with mRNA-based vaccines contains SARS-CoV-2 neutralizing antibodies that could potentially provide protection to breastfed infants from infection.

Impact of COVID-19 Pandemic in Breastfeeding Consultations on LactApp, an m-Health Solution for Breastfeeding Support.

Introduction: Breastfeeding is an unquestionable right of mothers and their children; however, it is not a one-woman job. For breastfeeding to succeed, women must have access to appropriate support and guidance. The COVID-19 pandemic and subsequent restriction measures and lockdown to reduce community spread of the disease have negatively impacted breastfeeding support from health services and thus, in mothers' breastfeeding experiences. Objective: The present study aims at evaluating the impact of the COVID-19 pandemic on breastfeeding consultations in LactApp (a mobile application [app] for m-Health focused on breastfeeding support, www.lactapp.com) during the COVID-19 pandemic. Materials and Methods: We conducted an observational, descriptive, and retrospective study with LactApp data recorded between July 2018 and March 2021, including 9,151,456 queries classified in 48 topics among 137,327 active users. We used the Interrupted time series model to evaluate the increase of the number of queries consulted and active users due to the COVID-19 pandemic. Wilcoxon test was used to study the increase of certain topics due to the COVID-19 pandemic. Results: LactApp active users increased by 12,092 users (p < 0.001) during the COVID-19 outbreak and confinement and queries consulted in LactApp also significantly increased by 10,899 queries per month after the pandemic outbreak. The breastfeeding topics that significantly increased are those related to growth spurts, breastfeeding stages, breastfeeding technique, breast pain and mastitis, problems with infants not gaining weight correctly, hypogalactia, increased milk demand, and relactation. These findings are important to understand the potential of online tools when face-to-face professional support is unavailable. Conclusions: Critical issues in breastfeeding establishment were highly consulted and significantly increased in the app during the pandemic. We believe that LactApp was a useful tool for breastfeeding support when women could not obtain appropriate support elsewhere. LactApp might be considered a powerful tool to identify critical issues of breastfeeding and trends in an automatized manner.

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.

BACKGROUND: Breast milk is a vehicle to transfer protective antibodies from the lactating mother to the neonate. After SARS-CoV-2 infection, virus-specific IgA and IgG have been identified in breast milk, however, there are limited data on the impact of different COVID-19 vaccine types in lactating women. This study is aimed to evaluate the time course of induction of SARS-CoV-2-specific IgA and IgG in breast milk after vaccination. METHODS: In this prospective observational study in Spain, 86 lactating women from priority groups receiving the vaccination against SARS-CoV-2 were included. Breast milk samples were collected longitudinally at seven or eight-time points (depending on vaccine type). A group with confirmed SARS-CoV-2 infection (n=19) and a group of women from pre-pandemic time (n=20) were included for comparison. RESULTS: Eighty-six vaccinated lactating women [mean age, 34.6 ± 3.7 years] of whom 96% were Caucasian and 92% were healthcare workers. A total number of 582 milk samples were included, and vaccine distribution was BioNTech/Pfizer (BNT162b2, n=34), Moderna (mRNA-1273, n=20), and AstraZeneca (ChAdOx1 nCoV-19, n=32). For each vaccine, 7 and 8 longitudinal time points were collected from baseline up to 30 days after the second dose for mRNA vaccines and adenovirus-vectored vaccines, respectively. A strong reactivity was observed for IgG and IgA after vaccination mainly after the 2nd dose. The presence and persistence of specific SARS-CoV-2 antibodies in breast milk were dependent on the vaccine type, with higher IgG and IgA levels in mRNA-based vaccines when compared to AstraZeneca, and on previous virus exposure. High intra- and inter-variability were observed, being relevant for IgA antibodies. In milk from vaccinated women, anti-SARS-CoV-2 IgG was significantly higher while IgA levels were lower than in milk from COVID-19-infected women. Women with previous COVID-19 increased their IgG antibodies levels after the first dose to a similar level observed in vaccinated women after the second dose. CONCLUSIONS: COVID-19 vaccination induced anti-SARS-CoV-2 IgA and IgG in breast milk with higher levels after the 2nd dose. Levels of anti-SARS-CoV-2 IgA and IgG are dependent on the vaccine type. Further studies are warranted to demonstrate the protective antibody effect against COVID-19 in infants from vaccinated and infected mothers. TRIAL REGISTRATION: NCT04751734 (date of registration is on February 12, 2021).