The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes severe respiratory tract infections in humans (COVID-19), has become a global health concern. Currently, several vaccine candidates against SARS-CoV-2 are in clinical trials but approval of these vaccines is likely to take a long time before they are available for public use. In a previous report, the importance of passive immunity and how immunoglobulin (Ig)G collected from recovered coronavirus patients could help in the protection against COVID-19 and boost the immune system of new patients was reported. Passive immunity by immunoglobulin transfer is a concept employed by most mammals and bovine IgG has a role to play in human therapy. IgG is one of the major components of the immunological activity found in cow’s milk and colostrum. Heterologous transfer of passive immunity associated with the consumption of bovine immune milk by humans has been investigated for decades for its immunological activity against infections. This short review focuses on passive immunity and how microfiltered raw immune milk or colostrum collected from cows vaccinated against SARS-CoV-2 could provide short-term protection against SARS-CoV-2 infection in humans and could be used as an option until a vaccine becomes commercially available.

Currently, different academic institutions and pharmaceutical companies worldwide have started programs to develop and test vaccine candidates against SARS-CoV-2 in clinical trials. An S-glycoprotein-based vaccine is a promising approach that has attracted the attention of scientists, since S-glycoprotein can be directly recognized by the host’s immune system. For the first coronavirus (SARS-CoV-1), which was identified in Guangdong province, China, in November 2002, different vaccines were developed and tested in animal models. Some of these vaccines prevented animal infection after challenge with SARS-CoV-1. Kapadia et al. showed that neutralizing antibodies against SARS-CoV-1 could be detected in sera from mice immunized with S-glycoprotein of SARS-CoV-1 (10, 11).