Wednesday, October 14, 2020

Could an existing vaccine make COVID-19 less deadly? Mexico City study provides support

I wonder if part of the reason young people are less likely to get severe cases of Covid-19 is that they have usually had MMR vaccine more recently than older people?  After I got the swine flu shot, I didn't get sick for three years.


News Release 14-Oct-2020
A prospective observational study testing the concept of trained immunity for protection from severe COVID-19 reported milder symptoms in COVID patients receiving MMR vaccination, as published in Allergy.
Parsemus Foundation

COVID-19 continues to wreak havoc globally, with over one million deaths to date. Yet what if an existing vaccine could make COVID-19 less deadly? A study just published put the theory to test, with promising results.

A research team led by Dr. Larenas-Linnemann working at Medica Sur, Mexico City, reported on their clinical observations in 255 subjects vaccinated with the mumps-measles-rubella (MMR) vaccine since the start of the Coronavirus disease-2019 (COVID-19) pandemic. Many vaccinated patients were family members or caregivers of patients who already had contracted COVID-19, and thus at extremely high risk. Thirty-six of the patients have now contracted COVID-19, but all with a remarkably mild course, with less severe symptoms than would be expected given their health status and age. The paper, published in the September issue of Allergy, the European Journal of Allergy and Immunology, is now available for free download.


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Since COVID-19 was new to humans, there was no existing treatment or vaccine to specifically fight it. But Dr. Larenas-Linnemann, being Dutch and having done her basic training in the Netherlands, had followed with admiration the work of a fellow countryman on a little-known concept called "trained immunity." In technical terms, trained immunity refers to the enhanced immune response to a certain pathogen, after being exposed (by vaccination or natural illness) to another non-related pathogen; the immune reaction after a subsequent exposure to a non-related pathogen is faster in onset and accompanied by an increased production of certain cytokines. This means that, surprisingly, some vaccinations could not only prevent the target disease (such as measles), but also help people fight other diseases.

Trained immunity is a form of non-specific immunity. It was controversial at first, but after decades of pioneering fieldwork from a Danish team studying the tuberculosis vaccine and the live polio vaccine in both Northern Europe and Africa, followed by years of authoritative laboratory work from Dr. Larenas-Linnemann's countryman Mihai Netea and others, it is now accepted that certain live-attenuated vaccines can make the body better prepared to fight off a range of pathogens.

Dr. Larenas-Linnemann's team wondered: Could a live-attenuated vaccine be protective against this entirely new disease, COVID-19, for their patients? Taking advantage of the fact that the pandemic in Mexico coincided with a rise in measles cases, which had motivated the Ministry of Health to recommend measles re-vaccination, the team decided to put the concept of trained immunity to the test. As such, from March 2020 onward, the researchers recommended MMR vaccination to their patients, especially among family members of COVID-19 cases.


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Dr. Larenas-Linnemann's team instead chose the MMR vaccine for its safety profile, as well as for previous research describing trained immunity from MMR in newborns of hepatitis-infected mothers and retrospective studies showing 26-49% decreases in all-cause mortality rates after measles vaccination programs.

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With funding from the Parsemus Foundation and Fast Grants, the MMR randomized controlled trial is enrolling first responders and healthcare workers in the hard-hit New Orleans region. Dr. Fidel's team is still seeking funding to test whether MMR can provide protection to nursing home residents, who are particularly vulnerable to this disease. 


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