The novel coronavirus SARS-CoV-2 that has ripped across the planet causing a global pandemic has served as a stark reminder of what life would be like without vaccinations. While no vaccine has yet been developed to protect against SARS-CoV-2 or any other coronavirus, a paper published in mBio, a journal of the American Society for Microbiology, reveals that the measles, mumps and rubella (MMR) vaccine may have benefits for swerving the worst symptoms of Covid.
Part of Covid’s lethality is due to septic inflammation, which causes reduced blood flow to limbs and major organs, resulting in organ failure and even death. Whilst neither measles, mumps nor rubella are a part of the coronavirus family, there is evidence that vaccines can provide nonspecific protection against lethal infections outside of the vaccine’s specific remit. This happens as the prophylactic treatment essentially trains immune cells in the bone marrow to respond more efficiently to infections in general.
Building on research from other countries, the team looked at the example of a lab using live attenuated Mycobacterium bovis (BCG) vaccine against lethal polymicrobial sepsis. They discovered the observed protection against sepsis was the result of long-lived myeloid-derived suppressor cells (MDSCs) which were already known to suppress septic inflammation. The researchers are now going to conduct a clinical trial into the efficiency of MMR as a low-risk, high-reward treatment that has the potential to induce MDSCs in frontline staff most at risk from disease. The MMR vaccine is known to be safe for use in humans and given Covid-19 is strongly associated with the kind of lung inflammation and sepsis protected against by MDSCs, the researchers believe it’s a promising area for investigation.
The theory is supported by the example of the USS Roosevelt, where of the 955 sailors who tested positive on board, only one required hospitalization. The researchers say this could be in part due to the fact that the MMR vaccinations are given to all US Navy recruits. There have also been fewer deaths reported in areas where MMR vaccines are routinely given, and milder symptoms in children could potentially be explained due to their more recent and frequent exposure to live attenuated vaccines.
"If adults got the MMR as a child they likely still have some level of antibodies against measles, mumps, and rubella, but probably not the myeloid-derived suppressor cells," said Dr Paul Fidel, Department Chair, Oral and Craniofacial Biology, and Associate Dean for Research, Louisiana State University Health School of Dentistry, in a statement. "While the MDSCs are long-lived, they are not life-long cells. So, a booster MMR would enhance the antibodies to measles, mumps, and rubella and reinitiate the MDSCs. We would hope that the MDSCs induced by the MMR would have a fairly good life-span to get through the critical time of the pandemic."
Fidel co-authored the perspective article based on ideas stemming from research in their respective labs with Dr Mairi Noverr, Professor of Microbiology & Immunology at Tulane University School of Medicine in New Orleans. Without the results of a clinical trial, the benefits of the MMR vaccine in beating Covid cannot be confirmed, but the researchers suggest that given its safe use, administering the MMR vaccine realistically presents little risk to those receiving it.
"While we are conducting the clinical trials, I don't think it's going to hurt anybody to have an MMR vaccine that would protect against the measles, mumps, and rubella with this potential added benefit of helping against COVID-19,” Fidel concluded.