COMPARATIVE EFFECTIVENESS OF mRNA, INACTIVATED, AND VIRAL-VECTOR VACCINES IN PREVENTING INFECTIOUS DISEASES

The review compared three key vaccine platforms, mRNA, inactivated and viral vectors, to control infectious disease using COVID-19 as a prototype, but also with further insights into polio, RSV and Ebola. After 18 months of follow-up with subgroup analyses and summary safety profiles of 18,000 participants in a multicenter prospective cohort, vaccine efficacy was highest with mRNA vaccines: 71% against infection, 84% against severe disease and 88% against death, versus inactivated and viral vector vaccines. Inactivated vaccines, with less effective protection against infection, still offered great and important protection against hospitalization and death, particularly in younger people, and retained the safety and operation benefits of safety, simplicity and coverage. Viral vector vaccines offered partial protection but were most appealing in an outbreak by virtue of single dose administration with limitations owing to isolated cases of thrombosis. Age-stratified analyses revealed reduced efficacy in older participants, particularly inactivated vaccines, which reinforced the importance of booster dosing and mixed schedules. Bad events in all the platforms were generally mild or moderate, and serious adverse events like myocarditis or thrombosis remained extremely rare. These observations indicate that despite the high bar of efficacy posed by mRNA technology, diversification of platforms is essential to enable global vaccine equity, response to outbreaks, and pandemic preparedness.