Journal of Vaccines & Vaccination

Effect of Breakthrough Infection on the Spread of COVID-19 Evaluated by a Flexible Compartment Model

Hiroo Ohmori^* Department of Natural Environmental Studies, The University of Tokyo, Kashiwa city, Japan
^*Correspondence: Hiroo Ohmori, Department of Natural Environmental Studies, The University of Tokyo, Kashiwa city, Japan, Email:

Received: 03-Oct-2024, Manuscript No. JVV-24-27102; Editor assigned: 07-Oct-2024, Pre QC No. JVV-24-27102 (PQ); Reviewed: 21-Oct-2024, QC No. JVV-24-27102; Revised: 28-Oct-2024, Manuscript No. JVV-24-27102 (R);

Introduction

A live attenuated vaccine such as the MMR vaccine may be used to “train” innate immune cells to be stronger and function more effectively against foreign virus insults. Globally, patients who tested positive for COVID-19 and were 50 years old above exhibited severe higher mortality rates. Currently, a vaccine for COVID-19 has not yet been established and herd immunity has a low possibility of occurring in many countries until then. COVID-19 is a contagious virus that can be rapidly spread in airborne droplets, but MMR vaccination can minimize the quantity of viral progeny within a host and immobilize the virus from spreading systematically. Specifically, the MMR vaccine’s effect mobilizes leukocytes precursors subsiding in the bone marrow such as monocytes, macrophages and granulocytes. In addition, the MMR vaccine contains similar amino acid residues that are present on the COVID-19 virus, which allowed for cross reactivity of the MMR vaccine to neutralize the COVID-19 virus. In theory, MMR vaccination can be used as a preventative measure for COVID-19 positive patients and reduce the mortality rate.

Literature Review

Many countries who have extended MMR vaccination beyond childhood have seen low death rates in COVID-19 positive patients with severe symptoms. In Hong Kong, which instituted a free MMR vaccination program for all healthcare professionals as well as made vaccination available for all adults in 2019, the data showed only 34 people have died from COVID-19 as of July 2020. Hong Kong’s proximity to Wuhan, China is 563 miles away and is the 4th most dense city in the world. In Madagascar, which recently vaccinated their population of 7.2 million people with Measles and Rubella-Containing Vaccines (MRCV) in 2019, the data showed that only 16 people have died from COVID-19 as of June 2020. In South Korea, in addition to childhood immunization, military recruits are all required to be administered with two doses of MMR prior to entry. Since every male joins the military in South Korea between the age of 18 to 28 years old, there is a possibility of maximum immunity to MMR viruses. This conferred stronger immunity showed an association to the low incidence of COVID death rates compared to neighboring countries. A core similarity among the countries that have a low COVID-19 mortality rate is the recent MMR vaccination of two doses separated by 28 days, instead of one single dose. These countries include Vietnam, Laos, Mongolia, Nepal, Maldives, Libya, Djibouti, Republic of Georgia, El Salavador, Uruguay, Nicaragua, Guatemala, Belarus, Armenia, Oman, Somalia, Azerbaijan, Cambodia, Sri Lanka, Papua New Guinea and Micronesia.

Expanding upon the evidence of MMR vaccination as a preventative measure for COVID-19 patients, the U.S.S. Roosevelt’s case can be examined. All 1102 people on board were tested positive for COVID-19, but there was only one death, seven people hospitalized and zero people in the ICU. Similarly to South Korea, all new recruits were given new MMR vaccinations prior to entry regardless of their vaccination records [1]. The data on the U.S.S. Roosevelt showed that the age range of the recruits were between 20-44 which would translate to a hospitalization rate of 14.3%-20.8% but these recruits had a 0.6% hospitalization rate due to the new MMR vaccination. This rate difference is 20 times lower compared to the general population that only has a single dose of MMR and no updated vaccination. This data showed the significance of a MMR booster due to low incidences of death and hospitalization among 1102 people [2].

Discussion

Healthcare providers in the U.S who have received 2 doses of MMR have a lower mortality rate compared to the average adult who doesn’t work in a healthcare setting and only receive 1 dose of MMR. Despite working in a “high risk” environment, the mortality rate of healthcare providers in the U.S is less compared to the number of deaths in the overall population. According to the CDC as of July 31^th, 2020, the number of COVID-19 cases among healthcare personnel was 119,639 and the number of deaths was 587 [3]. This translates to a 0.5% mortality rate for the healthcare personnel. In comparison, the total cases of COVID-19 in the population was 4,473,974 and the number of deaths was 151,499. The overall population mortality rate is 3.38%. The low mortality rate may be attributed to the diverse vaccination schedule that includes an additional MMR booster prior to work entry. The 2 doses of MMR may be an outstanding factor that prevented the high mortality rate of positive cases in healthcare personnel [4].

There are countries that do show contrasting data with MMR two dose vaccination instead of one dose. Belgium started the vaccination with two doses after 1995 and had no prior vaccination of MMR until 1985. With a larger population than Hong Kong by 54%, it has 9,732 deaths as of June 2020. Iran is another country that implemented a new MMR vaccination plan for its population of 33 million. Due to the long-standing measles outbreak in Iran, the ministry of health and medical education decided to outline a new strategy in 2003 to vaccinate all persons aged above 5-25 years old with a combination of measles and rubella. Prior to 1971, less than 37% of Iran’s population was vaccinated against measles. After the campaign in 2003, 99% of the population had vaccination coverage but there was a re-emergence of measles outbreak again in 2009. The re-emergence was due to the primary failure of the vaccine [5]. The primary failure can be influenced by factors like age at the time of vaccination, hazardous administration of the vaccine, reduced immunity of the individual and strain of the virus used in the manufacturing process. These factors may be the underlying reason for the current increasing cases of COVID-19 and higher mortality rate in Iran. Italy is another country with contrasting data with MMR vaccination. In March, Italy was one of the hardest hit countries in Europe for COVID-19 cases. This may be due to a low MMR vaccination rate of 85% compared to neighboring countries in Europe which were above 91%. The lower vaccination rate was attributed to a modern concept known as vaccine hesitancy that prevented vaccination protection against the MMR virus in Italy. People who were resistant to vaccination formed this decision from various factors such as context, environment, people, historical period and a single vaccine. These factors among various countries may be an explanation for the discrepancy surrounding the effect of the MMR vaccine [6].

Countries that implemented the MMR booster for its high risk groups and yet had high mortality rates were evident of the various factors that played a significant role in the prevention of COVID-19. These factors include but are not limited to access to Personal Protection Equipment (PPE), low socioeconomic status, geographic regions, limited COVID-19 testing, physical distancing, wait time for test results, contact tracing, underlying comorbidities and limited access to healthcare services [7]. The same factors also apply to healthcare providers. Despite being vaccinated against MMR, there were still cases of COVID-19 positive among healthcare providers. Due to the “high risk” environment that exposes healthcare providers to COVID-19, the risk of transmission is higher compared to the average adult who doesn’t work in healthcare settings. Furthermore, healthcare providers in the U.S lacked the necessary PPE and disinfectants to protect themselves and keep their environment sterile while fighting the virus. These limitations need to be addressed in order to validate the benefits and protection of the MMR booster for severe symptoms of COVID-19 in different countries [8].

Conclusion

In conclusion with the administration of a MMR booster, studies have shown low incidences of death, low cases in the ICU, low hospitalization rates and increased immunity to different viral families because of the shared similar residue component found between the rubella virus in the MMR vaccine and COVID-19. There are still many limitations that prevent the use of a MMR booster due to the early stages of investigations and lack of patient-level on long-term coverage. Furthermore, the limitations need to be addressed within countries that have differences in vaccination practice. However if this theory is correct and the MMR vaccine can be used as a preventative measure for severe symptoms due to COVID-19, then it is an accessible vaccine that can save hundreds of thousands of lives in this turbulent and critical time.

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