Researchers Investigate Whether MMR Vaccine Is Protective Against COVID-19

A pair of researchers in New Orleans have a novel suggestion: Harness the power of live attenuated vaccines – the MMR in this case – to help reduce the septic inflammation associated with COVID-19. Find out why the authors suggest MMR vaccination in some adults, including healthcare workers, even before a clinical trial is conducted.

NEW ORLEANS – Could the measles, mumps, rubella vaccine help reduce septic inflammation associated with COVID-19 infection?

An article in mBio, a journal of the American Society for Microbiology, suggests that could be the case.

https://mbio.asm.org/content/11/3/e00907-20

The co-authors – spouses Paul Fidel, Jr., PhD, of Louisiana State University Health School of Dentistry, and Mairi Noverr, of Tulane University School of Medicine, both in New Orleans – wrote a perspective article on the topic.

The pair make their proposal with the understanding that vaccination with MMR in immunocompetent individuals has no contraindications and might be especially effective for healthcare workers at risk of exposure to COVID-19.

“Live attenuated vaccines seemingly have some nonspecific benefits as well as immunity to the target pathogen. A clinical trial with MMR in high-risk populations may provide a low-risk-high-reward preventive measure in saving lives during the COVID-19 pandemic," Fidel pointed out. "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."

In an experiment, the authors demonstrated that vaccination with a live attenuated fungal strain-induced trained innate protection against lethal polymicrobial sepsis. They explain that the protection was mediated by long-lived myeloid-derived suppressor cells (MDSCs) previously reported inhibiting septic inflammation and mortality in several experimental models. The researchers posit that an MMR vaccine should be able to induce MDSCs to reduce severe lung inflammation/sepsis associated with COVID-19, which is strongly associated with mortality in the infection.

Fidel and Noverr question, for example, whether milder symptoms among 955 sailors on the U.S.S Roosevelt who tested positive for COVID-19 – which led to only one hospitalization – might have been a result of universal MMR vaccination of all Navy recruits. They add that epidemiological data suggests a correlation between people in geographical locations who routinely receive the MMR vaccine and reduced COVID-19 death rates.

Furthermore, according to the authors, COVID-19 has had a lesser impact on children, possibly because of their more recent exposure to live attenuated vaccines that can also induce the trained suppressive MDSCs that limit inflammation and sepsis.

While the researchers propose a clinical trial to test whether the MMR vaccine can protect against COVID-19, they also urge that adults, especially healthcare workers and individuals in nursing homes get the MMR vaccine.

 "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," Fidel emphasizes. "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."

“Following the lead of other countries conducting clinical trials with the live attenuated Mycobacterium bovis BCG (BCG) vaccine under a similar concept, a clinical trial with MMR in high-risk populations may provide a ‘low-risk–high-reward’ preventive measure in saving lives during this unprecedented COVID-19 pandemic,” the authors write.