The administration of a vaccine unrelated to the novel coronavirus, such as the one used for measles, mumps, rubella, or MMR, may serve as a preventive measure against the worst disease complications of COVID-19, scientists say.
Researchers, including those from the Louisiana State University in the US, said live attenuated vaccines, which are made using weakened strains of a disease causing pathogen, provide nonspecific protection against lethal infections.
They said these vaccines can induce "trained" innate immune cells for improved host responses against subsequent infections.
In the study, published in the journal mBio, they said vaccination with MMR in immunocompetent individuals may be effective for healthcare workers who can easily be exposed to COVID-19.
The researchers speculated that adults who had received the MMR vaccine in childhood likely still possess antibodies against the targeted viruses which at the very least would provide added protection against measles, mumps, and rubella for older adults.
With the added induction of the immune system's trained innate cells, they believe MMR vaccination could also provide protection against the "worst sequelae of COVID-19."
"In direct support of this concept, it was recently reported that the milder symptoms seen in the 955 sailors on the USS Roosevelt who tested positive for COVID-19 may have been a consequence of the fact that MMR vaccinations are given to all US Navy recruits," the scientists wrote in the study.
The researchers have called for a clinical trial with MMR in high-risk populations, suggesting it may provide a "low-risk high-reward" preventive measure in saving lives during the pandemic.