A systematic review of immunogenicity of Covid-19 vaccines in milk and serum of breastfeeding mothers based on existing evidence

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines are administered worldwide. However, lactating women have been excluded from clinical trials, and limited information is available on the safety of vaccines against SARS-CoV-2 in lactating women. Therefore, comprehensive information is needed for mothers to make informed decisions about the need for vaccination to control the spread of the virus. This review study was conducted aimed to know the necessity of vaccination of breastfeeding mothers against the SARS-COV2 virus and to know the immune responses created in plasma and breast milk after the injection of COVID-19 vaccines.

In this systematic review study, Google Scholar, PubMed, and Science Direct information sources were used in the period of 2021 to 2022 to extract research articles containing information and the safety of milk and serum of lactating mothers vaccinated against SARS-COV-2. The articles which were not related to the purpose of the article were removed from the study process.

Out of 1770 articles related to the initial search, data from 30 papers met the inclusion criteria. Among the available vaccines, only the effects of AstraZeneca, Pfizer, and Moderna vaccines wereidentified on antibody secretion in breast milk and serum. The results of the presentresearch confirmed the presence of anti-SARS-CoV-2 antibodies in vaccinated serum and breast milk. So, IgG was the predominant antibody reported in many studies after vaccination.Thus, unlike post-viral immunity, the specific response of the vaccine is to dominate IgG and not IgA.The role of IgM was also less than that of other antibodies.

Vaccination of lactating mothers enhances the protective effects of milk against COVID-19 infection. More efforts are needed to encourage breastfeeding mothers to be vaccinated and support breastfeeding during the outbreak.