COVID-19: MMR and Tdap vaccines may reduce severity of COVID-19
For some time now scientists hypothesized that immune memory for other viruses could potentially reduce severity of COVID-19 as well. 🧵1/
For some time now scientists hypothesized that immune memory for other viruses could potentially reduce severity of COVID-19 as well. 🧵1/
Analysis of a large and well-characterized COVID-19 patient cohort revealed that prior MMR (measles-mumps-rubella) and Tdap (tetanus-diphtheria-pertussis) vaccination associates with reduced disease severity and death ( cell.com/med/fulltext/S… ). 2/
How is that possible? A diverse immune T cell response controls viral infections and a major goal of vaccines is to induce a strong and durable T cell memory. Reactivation of memory T cells generated against a different pathogen could enhance immunity to novel pathogens. 3/
Researchers were able to show that pre-existing memory T cells from previously administered MMR and Tdap vaccines are reactivated when infected with COVID-19 or introduction of COVID-19 vaccine spike proteins and have a memory T cell subset implicated in antiviral immunity. 4/
T-cell receptors (TCR) are found on the surface of immune T cells and are responsible for recognizing fragments of a pathogen (antigen). Identical TCRs are shared on COVID-19, MMR, and Tdap generated immune T cells. 5/
The study found the incidence of disease severity was reduced by 32%-38% for those who had received the MMR vaccine and 20%-23% for those who received the Tdap vaccine. 6/ 
The researchers conclude that Tdap and MMR memory T cells that are reactivated by COVID-19 may provide protection against severe COVID-19. 7/
Not only do the COVID-19 vaccines provide strong protection against severe disease, it seems the MMR and Tdap vaccines your parents got for you may also provide some protection. 8/
Two doses of the MMR vaccine should provide protection for life, while the Tdap vaccine requires boosters every 10 years. 9/
COVID-19 in general is less severe in younger children than older adults. I wonder if part of that comes from the fact that most children more recently had MMR and Tdap vaccines which may provide them with additional protection compared to older adults? 10/
At least this may be for the children that are still getting their standard vaccines these days. Vaccines are not only good for the viruses they were designed for but as you can see in this study, for some new future viruses as well. 11/
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