November 20, 2020

expert reaction to study looking at MMR antibodies and COVID-19 disease severity

A study published in mBio looks at Measles-Mumps-Rubella (MMR) antibodies and COVID-19 disease severity.

Dr Penny Ward, Visiting Professor in Pharmaceutical Medicine at King’s College London and Chair of the Education and Standards Committee of the Faculty of Pharmaceutical Medicine, said:

“Regrettably the paper presented is significantly flawed in that the comparator groups are not matched for important criteria, not least age, which affects the pattern of disease among individuals with COVID infection and ergo the analysis is itself invalid.  In addition the authors have not specifically prospectively followed individuals to document a reduced infection/case rate associated with MMR vaccination in later life – contrast with the recent results from trials of SARS CoV2 specific vaccines, which are clearly highly effective in preventing disease.

“The potential that vaccination against non related diseases might confer protection against other infections has been investigated in the past, ironically because of concerns expressed by some communities that the ‘burden’ of frequent childhood vaccinations might cause ‘immune overload’ and prevent normal responses to non vaccine related infections.  Two previous (pre-COVD) studies demonstrated less morbidity and reduced overall risk of any serious infection among vaccinated compared to unvaccinated populations, which suggests that vaccination might stimulate general immune reactivity against non related pathogens, and indeed this has been observed not only with MMR but also with BCG vaccination in some settings.

“Environmental exposure to non vaccine pathogens dwarfs exposure to vaccine specific pathogenic organisms, as vaccination protects against sustained transmission of these in communities, as long as a satisfactory level of vaccination is achieved for the vaccine specific disease of interest (this is 95% in the case of measles).  It would therefore not be appropriate to suggest that an entire population receive vaccination with the live attenuated MMR vaccine in order to prevent COVID, as this study does not demonstrate specific protection from COVID.

“It is however important to support the continued vaccination of children with the recommended vaccines including MMR, HiB, MNY etc to ensure that they protected against these, for them equally important and potentially life threatening diseases.  Another reason for children, particularly young children, not being vectors of SARS CoV2 infections is that they generally have limited ACE2 receptors in the respiratory tract; SARS CoV2 requires the presence of the ACE2 receptor to infect respiratory tissue.  ACE2 receptor density increases after puberty and during adult life, and this is a possible additional explanation for the age related incidence of severe infection in older persons.”

Dr Simon Clarke, Associate Professor of Cellular Microbiology at the University of Reading, said:

“The authors of this study show that people with higher amounts of antibodies reactive to the mumps virus, had less severe Covid-19 symptoms.  Unfortunately, the authors appear not to have determined the total concentration of antibodies in the blood of these patients, so it might be the case that they just had higher concentrations of all antibodies in their blood, not just those which are reactive to mumps.  This merely demonstrates a correlation, which as always is not evidence of causation.  There is no confirmation that it is the anti-mumps antibodies that is causing the decrease in severity of symptoms.”

‘Analysis of Measles-Mumps-Rubella (MMR) Titers of Recovered COVID-19 Patients’ by Gold et al. was published in mBio on Friday 20 November 2020.

DOI: 10.1128/mBio.02628-20

https://mbio.asm.org/content/11/6/e02628-20

Declared interests

Dr Penny Ward: “No COIs. I am semi-retired, but I am owner/Director of PWG Consulting (Biopharma) Ltd a consulting firm advising companies on drug and device development.  Until July 2019 I was Chief Medical Officer of Virion Biotherapeutics, which was a company developing broad spectrum RNA therapy for the treatment/prevention of respiratory virus infections.  Between December 2016 and July 2019 I served as Chief Medical Officer of Virion Biotherapeutics Ltd, a company developing antiviral treatments for respiratory viral diseases.  Previous employee of Roche, makers of tocilizumab (anti IL6 antibody) and CMO of Novimmune, makers of empalumab (anti IFN gamma antibody).”

None others received.