The measles-mumps-rubella (MMR) vaccine has been theorised to provide protection against Covid-19, according to a new study published in mBio, an open-access journal of the American Society for Microbiology.

Researchers as part of the study analysed the correlation between the antibodies produced by the MMR vaccine and severity in patients recovered from Covid-19. They found that mumps IgG titers, or levels of IgG antibody produced by the MMR vaccine, are inversely correlated to severity in Covid-19 patients.

As per the report, MMR II contains the Edmonston strain of measles, the Jeryl Lynn (B-level) strain of mumps, and the Wistar RA 27/3 strain of rubella.

Researchers divided 80 subjects into 2 groups as part of the study. Out of these, 50 subjects had been vaccinated using the MMRII vaccine, who would primarily have MMR antibodies. They were compared to a group of 30 subjects who had no record of MMR II vaccinations. They would primarily have MMR antibodies from other sources, including prior measles, mumps, and/or rubella illnesses.

The researchers found a significant inverse correlation between mumps titers and Covid-19 severity within the MMR II group.

In the group who had no history of vaccination, there were no significant correlations between mumps titers and disease severity. Titers were measured through Quest Diagnostics using their standard diagnostic protocol.

“Within the MMR II group, mumps titers of 134 to 300 AU/ml (n=8) were only found in those who were functionally immune or asymptomatic. All with mild Covid-19 symptoms had mumps titers below 134 AU/ml (n=17). All with moderate symptoms had mumps titers below 75 AU/ml (n=11). All who had been hospitalised and required oxygen had mumps titers below 32 AU/ml (n=5),” the report stated.

“We found a statistically significant inverse correlation between mumps titer levels and Covid-19 severity in people under age 42 who have had MMR II vaccinations,” said lead study author Jeffrey E. Gold, President, World Organization, in Watkinsville, Georgia.

“This adds to other associations demonstrating that the MMR vaccine may be protective against Covid-19. It also may explain why children have a much lower Covid-19 case rate than adults, as well as a much lower death rate,” he added. The researchers will further investigate the efficiency of the vaccine in protecting against severe Covid-19 infection.

“The statistically significant inverse correlation between mumps titers and Covid-19 indicates that there is a relationship involved that warrants further investigation,” said co-author David J Hurley, PhD, Professor and Molecular Microbiologist, University of Georgia.