WHAT IF PREVIOUS IMMUNIZATION HAS IMPROVED OUTCOMES OF THOSE AFFECTED BY THE CORONA VIRUS? M. Norvell 3/20/20

     Historically, viral infections have the capacity to infect all that are exposed. They do not discriminate against race, sex or demographics. Given that we are all vulnerable, there are populations that have increased risk for complications which includes the very young, old, pregnant, immunocompromised and those with co-morbidites. So what is different now as this novel virus sweeps the world continent by continent. It’s the divide between the young and everyone else when comparing complication rates, severity and mortality. Yet, as all health professionals directly and indirectly involved in trying to develop a vaccine, or impose restrictions to contain what has now become known as COVID-19, the one question I have; why the young are surviving and the death rate is negligible when historically they are an at risk population. 

According to the World Health Organization (WHO) as of March 19, 2020, seven new countries have reported cases of COVID-19. The number of confirmed cases worldwide have surpassed 200,000. Frightening numbers as it took 3 months to reach 100,000 infected and only 12 days to surpass 200,000 (WHO, 2020). Currently, 256,802 confirmed cases and 10,501 deaths from the COVID-19 outbreak and preliminary data shows that all age groups can and are affected and maybe at the same rate but under 19 years old shows milder symptoms with no reported deaths in the United States (US)(CDC, 2020).

There are many theories floating about as to why the younger population has not been affected to the extent you would expect given they are generally susceptible. To put in layman terms, explanations range from a stronger immune system in the young and weaker in the old, continued exposure to human coronavirus in children or an over-reactive immune response and much more. As many theories are being derived on why infection rates probably mirror the same rate as those that are older, symptomology differs and ultimately mortality. There is not a significant amount of research data but beginning with the first SARS-CoV outbreak in 2002 and then again with MERS-CoV, children were also spared severity of illness (Stockman, et al., 2007) (Thatbet, et al., 2015) This is not to say that children and adolescence are not affected, but clinically symptoms have proven to be less and there were no deaths reported Worldwide in the SARS outbreak. (Stockman, et al., 2007) Potential and promising treatment of the SARS-CoV and MERS-CoV was the introduction of an attenuate live measles virus. In both SARS-CoV and MERS-CoV, both viruses showed promise in mice models. To simplify, these vaccines generally induce powerful humoral and cellular immune responses (Muhlebach, 2017) and highly immunogenic and protective in both MERS-CoV (Malcyzyk et al., 2015) and SARS-Cov (Escrow et al., 2014). Given the response of these studies, could a vaccines such as the MMR be a factor in why the younger population has less symptoms than the older population. They are closer to the immunization time line and still carry powerful humoral and cellular immune responses versus aging groups where particular immunities may be wearing off? Data was limited but there is a reason why the younger population is surviving and a stronger immune system cannot be the only cause as they succumb to virus past and present, but fair better with COVID-19. I believe more attention should be given to vaccine timelines, titer levels and potentially boosters that may stimulate immune response given the difference in severity of illness with COVID-19. 

A Highly Immunogenic and Protective Middle East Respiratory Syndrome Coronavirus Vaccine Based on a Recombinant Measles Virus Vaccine Platform.

Malczyk AH, Kupke A, Prüfer S, Scheuplein VA, Hutzler S, Kreuz D, Beissert T, Bauer S, Hubich-Rau S, Tondera C, et al. J Virol. 2015 Nov; 89(22):11654-67. Epub 2015 Sep 9.

CDC COVID-19 Response Team. MMWR Morb Mortal Wkly Rep. 2020 Mar 18. doi: 10.15585/mmwr.mm6912e2.

Muhlebach, MD. Virus Genes2017 Oct;53(5):733-740. doi: 10.1007/s11262-017-1486-3. Epub 2017 Jul 14.

Protection from SARS coronavirus conferred by live measles vaccine expressing the spike glycoprotein. Escrow,N., Callendret,B., Lorin,V, Combredet,C., Marianneau,Ph., Fevrier,M., Tangy,F. J Virol. Volume 452-453, March 2014, Pages 32-41.

World Health Organization (2020) Coronavirus disease 2019 (COVID-19) Situation Report – 59,https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200319-sitrep-59-covid-19.pdf?sfvrsn=c3dcdef9_2