MMR Vaccine Shows Some COVID-19 Protection

Desiree E.S. Larenas Linnemann, MD

New research shows the Mumps-Measles-Rubella (MMR) vaccine could provide some level of protection against more severe COVID-19 outcomes.

A team, led by Desiree E.S. Larenas Linnemann, MD, FAAAAI, Médica Sur Clinical Foundation and hospital, administered the MMR vaccine with 3 live-attenuated viruses to allergic patients and seemingly healthy close-contact of COVID-19 patients during the measles-outbreak between February and March 2020.

The Theory

There are several proteins produced by the SARS-CoV-2 virus that inhibit interferon (IFN) and IFN gene responses, which can abate the innate immune response during the initial infection.

In the past, researchers have found trained immunity following BCG or measles vaccination, an enhanced non-specific immune response to non-related pathogens. This can last up to a year for BCG, but might be too strong a stimulus, which is not advantageous for the cytokine storm-like syndrome in some patients with more severe COVID-19 infections.

The Study

In the study presented at the American Academy of Allergy, Asthma & Immunology (AAAAI) 2021 Annual Meeting, each patient was asked to contact the researchers if they have any COVID-19 symptoms or test positive for the virus. This subgroup of patients was asked to monitor daily vital signs, peak expiratory flow rate, and pulse oximetry.

The researchers used a simplified, out-patient scoring to rate their final COVID-19 severity.

Of the 587 patients who received the MMR vaccine, 79 tested positive for COVID-19. Of these patients, 12% were between 50-59 years old and 12% were between 60-75 years old. In addition, 40.5% (n = 32) had 1 or more risks factors, including morbid-obesity, diabetes, or hypertension, and 10 patients had asthma.

All of the COVID-19 positive patients had mild or moderate symptoms, with 2 requiring supplementary oxygen at home. In addition, 2 patients older than 70 were hospitalized and died, likely due to a pre-existing interstitial lung condition with a previous 2016 hospitalization for pneumonia and erroneously 2 administrations of the DTP vaccine 1-2 months prior to the MMR-II vaccine in another center.

“The here presented cases show a possible beneficial effect in the context of a COVID-19 infections,” the authors wrote. “Very recently another publication actually showed an inverse relationship between level of IgG against measles and COVID-19 outcome, with the mildest outcome in those with most antibodies.”

The researchers said prospective blinded studies are needed to confirm the initial findings.

COVID-19 Vaccines

There are currently 2 vaccines for COVID-19 available in the US—produced by Moderna and Pfizer-BioNTech.

Recently, the US Centers for Disease Control and Prevention (CDC) released a report showing relatively low rates of adverse events during the first month of administration in the US.

Overall, between Dec. 14 and Jan. 13 there was more than 13.7 million vaccine doses administered and 6994 reports of adverse events following vaccination. Of the adverse events, 6354 (90.8%) were deemed non-serious and 640 (9.2%) were classified as serious.

The study, “Recent Mumps-Measles-Rubella Vaccination Probably Reduces COVID-19 Severity: A Proposed Strategy For Close-Contacts Of Patients,” was published online by AAAAI 21.