Covid-19 vaccine trials have not included pregnant or breastfeeding women. Therefore, the use of these vaccines in this time interval has generated many doubts and concerns, as recognized the Spanish Association of Pediatrics. There were also doubts as to the possible transmission of covid-19 between infected women and their offspring through breast milk. But these, from now on, have more certainty about the safety of this food for their babies.
Two studies carried out by the Institute of Agrochemistry and Food Technology (IATA) of the Higher Council for Scientific Research (CSIC) and the Pediatric Service of the Hospital Clínico de Valencia demonstrate that breast milk from women who have been vaccinated or who have had the coronavirus disease is safe and contains specific antibodies against SARS-CoV-2.
Two studies, pioneers in Spain and the first in the world to compare the effects of three vaccines on breast milk, reinforce the idea that breastfeeding is safe and beneficial
“We have detected IgA and IgG antibodies against SARS-CoV-2 in breast milk of women who have had covid-19 and in women who have received vaccination,” explains Mª Carmen Collado, CSIC researcher at IATA-CSIC, who has co-led this investigation. “Now this is a small study, we need studies on a larger scale and with more families. We have detected antibodies but we have to study the impact of infection and vaccination on the composition of breast milk, as well as study the persistence of antibodies over time and their potential protective effect on the infant ”, explains Collado.
Infected women and breast milk
The two studies, pioneers in Spain and the first in the world to compare the effects of three vaccines on breast milk, reinforce the idea that breastfeeding is safe and beneficial in the midst of this pandemic.
In the first, a method has been developed to detect the presence of SARS-CoV-2 in the milk of infected women. “We recruited women who underwent PCR at the time of delivery by clinical protocol and tested positive. We collected breast milk samples and in none of those we analyzed did we find traces of the virus, in none. This is something very important, in most studies the presence of viruses had not been detected but in some particular studies they have detected virus particles. In our case, nothing. Our work supports the scientific evidence that indicates that breast milk is not a vehicle for the virus ”, remarks the IATA-CSIC researcher.
What they did find in these milks were antibodies. Specifically, the immunoglobulins IgA, IgG and IgM that act against structural proteins of SARS-CoV-2, the former being the ones that appeared in the highest proportion.
“Our work supports the scientific evidence that breast milk is not a vehicle for the virus.”
Vaccines and breastfeeding
In the second study, with a sample of 75 pregnant women, the presence of antibodies in milk was analyzed after the administration of three of the vaccines: 30 with a complete Pfizer vaccination, 21 with a complete Moderna regimen, and 24 with the first dose of AstraZeneca. The work demonstrated the presence of specific antibodies (IgA and IgG) in the samples, their presence being remarkable after the second dose.
“In addition, in this case we compared the generation of antibodies between women who had covid-19 and women who had not. The levels of antibodies that were reached in the milk of women who had passed the disease after the first dose of the vaccine are the same as those detected in women vaccinated with the complete regimen ”, describes Collado. As stated by the CSIC, this agrees with the information that suggests that individuals who have had the disease achieve immunity measured in blood with a single dose.
“There are many questions and we want to offer answers. As scientists, our obligation is to provide information, and that is what we are doing ”
And these investigations are only just getting started. The initiative MilkCorona, co-led by Collado and Dr. Cecilia Martínez Costa, from the Pediatric Service of the Hospital Clínico de Valencia, which also includes various hospitals, universities and research centers in the national territory, will continue “studying the persistence of these antibodies, what is the role of infection in the composition of milk and its relationship in the development of the infant microbiota and the maturation of the immune system ”, explains Collado.
“MilkCorona wants to scientifically address the questions related to covid-19 and breastfeeding. There are many questions and we want to offer answers. As scientists, our obligation is to provide information and that is what we are doing ”, he concludes.
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