Vaccines teach the immune system to recognize infectious agents or toxins and neutralize them. They create long-term immune memory by training special T and B cells (lymphocytes). Naturally, vaccines primarily protect against the diseases against which they are designed. However, their actions may have unexpected bonuses. For example, lymphocytes produced in response to a vaccine may have the ability to cross-react to other pathogens, including the SARS-CoV-2 coronavirus.
The authors of the new study studied T-cell receptors in the laboratory, obtained from the blood of people who have suffered from COVID-19. It turned out that they react to the SARS-CoV-2 spike protein in the same way as to the proteins of the MMR and DPT vaccines. Scientists write that this shows the presence of T cells that are capable of responding to several types of infection.
In addition to laboratory studies, scientists checked epidemiological data on the relationship between MMR and DPT vaccination with the severity of COVID-19. They analyzed data on 75 thousand patients who were treated for coronavirus infection at the Cleveland Clinic from March 2020 to March 2021. It turned out that the MMR vaccine was associated with a 38% decrease in the likelihood of hospitalization, and the risk of death and treatment in the intensive care unit – by 32%. Similar figures for vaccinated DPT are 23% and 20%.
Scientists indicate that further work is needed to study the relationship between MMR and DPT vaccination with the severity of COVID-19. At present, it is impossible to say for sure whether these vaccinations are the cause of the milder course of coronavirus infection.
“Our data shows that MMR and DPT vaccines are not a substitute for vaccines against COVID-19-19, but could possibly provide greater and longer lasting protection against emerging new variants of coronavirus than vaccines against COVID-19-19 by themselves. And in places where vaccines are against COVID-19-19 are not available, they can protect infected people from serious illness, ”said Tanya Mayadas of Harvard University, co-author of the study.
She added that during the pandemic COVID-19-19 there was a significant decrease in routine vaccination of children and adolescents. New evidence suggests its importance for both children and adults.