Protection against Severe Illness versus Immunity-Redefining Vaccine Effectiveness in the Aftermath of COVID-19

Renuka Roche; Nouha H Odeh; Abhay U Andar; Mohan E Tulapurkar; Joseph A Roche

doi:10.3390/microorganisms11081963

Protection against Severe Illness versus Immunity-Redefining Vaccine Effectiveness in the Aftermath of COVID-19

Microorganisms. 2023 Jul 31;11(8):1963. doi: 10.3390/microorganisms11081963.

Authors

Renuka Roche¹, Nouha H Odeh², Abhay U Andar³, Mohan E Tulapurkar⁴, Joseph A Roche⁵

Affiliations

¹ Occupational Therapy Program, School of Health Sciences, College of Health and Human Services, Eastern Michigan University, Ypsilanti, MI 48197, USA.
² Ph.D. Program in Immunology and Microbiology, Department of Biochemistry, Microbiology & Immunology, School of Medicine, Wayne State University, Detroit, MI 48201, USA.
³ Baltimore County, Translational Life Science Technology, University of Maryland, Rockville, MD 20850, USA.
⁴ Division of Pulmonary and Critical Care Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
⁵ Physical Therapy Program, Department of Health Care Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA.

Abstract

Anti-SARS-CoV-2 vaccines have played a pivotal role in reducing the risk of developing severe illness from COVID-19, thus helping end the COVID-19 global public health emergency after more than three years. Intriguingly, as SARS-CoV-2 variants emerged, individuals who were fully vaccinated did get infected in high numbers, and viral loads in vaccinated individuals were as high as those in the unvaccinated. However, even with high viral loads, vaccinated individuals were significantly less likely to develop severe illness; this begs the question as to whether the main effect of anti-SARS-CoV-2 vaccines is to confer protection against severe illness or immunity against infection. The answer to this question is consequential, not only to the understanding of how anti-SARS-CoV-2 vaccines work, but also to public health efforts against existing and novel pathogens. In this review, we argue that immune system sensitization-desensitization rather than sterilizing immunity may explain vaccine-mediated protection against severe COVID-19 illness even when the SARS-CoV-2 viral load is high. Through the lessons learned from COVID-19, we make the case that in the disease's aftermath, public health agencies must revisit healthcare policies, including redefining the term "vaccine effectiveness."

Keywords: SARS-CoV-2; cytokines; immunity; infectious diseases; public health.

Publication types

Review

Grants and funding

During the conceptualization and writing of this paper, RR and JAR received salary support and protected time for scholarship through their full-time, tenured faculty positions at Eastern Michigan University and Wayne State University, respectively. MET received salary support from Maryland Industrial Partnerships (MIPS) Grant #6907 to MET, and Veterans Affairs BLR&D Merit Award BX004270-04A1 to Hasday JD.