Human milk from women infected and vaccinated for coronavirus has antibodies against COVID-19

The studies are led by teams of the Institute of Agrochemistry and Food Technology (IATA-CSIC), with Institut de Recerca Sant Joan de Déu (IRSJD) and the University of Barcelona (UB), human milk from infected women and vaccinated for coronavirus has antibodies against COVID-19.

The main objective of the studies driven by the consortium is to study the impact of the natural infection by SARS-CoV-2 and the vaccination on human milk. Also, they intend to find out whether the immune response depends on the vaccination and whether the levels of antibodies towards SARS-CoV-2 are comparable to those in women who suffered COVID-19, apart from evaluating the impact of the vaccination on these women.

The studies are led by teams of the Institute of Agrochemistry and Food Technology (IATA-CSIC), the University of Barcelona (UB) and the Institut de Recerca Sant Joan de Déu (IRSJD). The MilkCorona consortium counts on the participation of the Department of Paediatrics of Hospital Clínic de València ─with the team led by the expert Cecília Martínez Costa─, the University Hospital Doctor Peset and the University and Technical Hospital La Fe, Hospital Clínic de Barcelona, IDIBAPS, Hospital San Cecilio de Granada, University Hospital Lozano Blesa in Zaragoza, and the Jaume I University and the University of Granada. Also, the initiative counts on the support of LactApp, a phone app on breastfeeding.

The first study developed and validated the method to detect SARS-CoV-2 in human milk in collaboration with the group led by the expert Glòria Sánchez (IATA-CSIC). According to the conclusions, they did not detect any remains of SARS-CoV-2 in the analysed milk samples. Also, most of the analysed samples presented a great variability of specific antibodies against coronavirus, both in naturally infected women and in vaccinated women. In the latter, the levels of antibodies varied depending on the vaccine they received. These are the first studies of such kind in Spain, and the first worldwide to compare the effects of the three vaccines in human milk.

No trace of coronavirus RNA in human milk

In particular, the study determined the presence of antibodies (immunoglobulins) IgA, IgG and IgM for structural proteins of SARS-CoV-2, like the named Receptor Binding Domain (RBD), an essential part of the virus that enables the infection of the cells, as well as in non-structural proteins, such as the main protease (MPRO). This protease has been analysed for the first time in human milk thanks to the technology carried out by the CSIC researcher Mar Valés and her team in the National Centre of Biotchnology (CNB-CSIC). The IgA antibodies were found in higher levels than the IgG and IgM in the human milk samples.

First study to compare the effects of three vaccines

In the second study, the team analysed the presence of antibodies against SARS-CoV-2 in 75 lactating women who had received different vaccines: 30 with full Pfizer vaccination, 21 with a full Moderna vaccination and 24 with the first dose of AstraZeneca. The study showed the presence of specific antibodies (IgA and IgG) in the analysed samples. Moreover, the levels of antibodies varied depending on the received vaccine, as well as on the existence of a previous infection. There was, in all cases, a response to the vaccination with an increase in antibodies for SARS-CoV-2 which was more intense after the second dose.

There were differences among the naturally infected women and those vaccinated with the higher presence of a type of antibody. Also, in some women who had been vaccinated with a dose after having had COVID-19, the human milk presented levels of antibodies equal to healthy women with two doses. This goes with the information that suggests that people who has had the disease gets immunity in the blood with an only dose.

"Breastfeeding is a priority, and we need more studies aimed at confirming the potential protecting role of these antibodies present in human milk regarding COVID-19 in children", notes María Carmen Collado, coordinator of the consortium and researcher at IATA-CSIC.

MilkCorona: an ongoing initiative

The MilkCorona initiative has received funding from La Marató de TV3 to launch a project in which the group led by Carmen Collado (IATA-CSIC) will do research on the impact of the infection and vaccination in the intestinal microbiota. As part of the funded project, the team led by Carles Lerín (IRSJD) will study the effects on the metabolic compounds of milk. The impact of the virus on the composition of immune elements in milk is the part to be analysed by the group led by Francisco José Pérez-Cano (UB-INSA), promoter of the 12th International Conference on Immunonutrition to take place next July, and distinguished for his studies on the role of diets and the immune elements of milk in the development of the immune system of lactating women both at a pre-clinic and clinical-scale.

The study by these teams continues to study new aspects on the impact and persistence of the new variants of coronavirus in the present antibodies in human milk, and the effect of the full vaccination with AstraZeneca. "We hope to provide new scientific data on the beneficial role of breastfeeding in this pandemic", note the members of the consortium.

Reference article

Bäuerl, C.; Randazzo, W.; Sánchez, G.; Selma-Royo, M.; Garcia-Verdevio, E.; Martínez-Rodríguez, L.; Parra-Llorca, A.; Carles Lerin, C.; Fumadó, V.; Crovetto, F.; Crispi, F.; Pérez-Cano, F.; Rodríguez, G.; Ruíz-Redondo, G.; Campoy, C.; Martínez-Costa, C.; Collado. M.C. "SARS-CoV-2 RNA and antibody detection in human milk from a prospective multicenter study in Spain". medRxiv, May 2021. Doi: 10.1101/2021.05.06.21256766

Selma-Royo, M.; Bäuerl, C.; Mena-Tudela, D.; Aguilar-Camprubí, L.; Pérez-Cano, F.; Parra-Llorca, A.; Lerin, C.; Martínez-Costa, C.; Collado. M.C. "Anti-Sars-Cov-2 IgA And IgG In Human Milk After Vaccination are Dependent On Vaccine Type And Previous Sars-Cov-2 Exposure: A Longitudinal Study". medRxiv, May 2021. Doi: 10.1101/2021.05.20.21257512