NEW DELHI: A new study has cited genomic evidence to propose that the oral polio vaccine might be protecting young Indians from Covid-19 through a process called cross-protection.
The long-term immune response generated by OPV might also protect from SARS-CoV-2 because of biological similarities it shares with OPV type I and type III viruses.
In the paper titled ‘Impact of Microbiota: A Paradigm for Evolving Herd Immunity against Viral Diseases’, researchers associated with the National Institute of Immunology have said while the entire world has a severe infection with SARS-CoV-2, there is a very low rate of death of infected children under 10.
Children who have received regular immunisation of different vaccines may have heterologous protection against Covid-19, the authors noted adding that in pan-India, the continuum of mass vaccinations with OPV, BCG, measles vaccine among others has established memory responses against many types of variable antigens in the body.
“A single-type or multiple-types of antibodies from the pool of the antibody mixture, present in the body, can recognise the novel pathogens carrying the same or similar types of antigens,” says the study.
This phenomenon is considered the major reason for the unexpectedly low rate of Covid-19 occurrence in India with a faster recovery rate.
Based on their analysis, the researchers have concluded that herd immunity is the most critical prophylactic (preventive) intervention, delivering the protective immunity against several infectious diseases such as smallpox, poliovirus and measle.
“The new paradigm of evolving herd immunity during a pandemic situation cannot be disregarded,” said the paper published recently.
“Crosstalk among microbiota, metabolism and environmental factors is critical for developing a competent immune system, which is a prerequisite for evolving herd immunity against any contagious infections.”
The scientists said the prevalence of heterologous immunity due to rigorous vaccination programmes at the grassroots level may provide protection against the SARS-CoV-2.
They added that the comparisons between SARS-CoV-2 human poliovirus type 3 offer great insights into the concept of heterologous immunity, which can be an alternative providing prophylactic intervention against both the poliovirus and Covid-19.