Researchers Chris P. Verschoor and George A. Kuchel open this perspective article, writing that the COVID-19 pandemic has illustrated that aging, especially when accompanied by chronic age-related comorbidities, is without doubt the most important factor of severe forms, complications and death of acute respiratory infections.
“In the absence of widely available and effective treatments, vaccines remain our most powerful tool to overcome this vulnerability, preventing primary infection but also, and even more importantly, improving clinical outcomes once the installed infection”.
In the case of SARS-CoV-2, the efficacy of the vaccine once morest hospitalization has been shown to be “remarkable” when circulating strains preceding Omicron, whereas for influenza or Streptococcus pneumoniae, this efficacy can vary from 80% to <10%, depending on the season and strain. Nevertheless, for these 3 pathogens,
Vaccine efficacy (VE) decreases with age,
which is explained by deficiencies in the ability of the immune system of the elderly to produce productive and persistent antibodies and/or to produce cell-mediated responses to the vaccine.
Further research on the contribution of lifestyle is needed: Because extremely large, expensive, and usually lengthy clinical trials are often required to reliably estimate VE, the vast majority of human vaccine studies assess immune correlates of protection as an indicator of VE. Thus, in these studies, antibody-related parameters such as neutralization capacity, are the most commonly used because they are technically simpler.
In conclusion, these experts call for completing these cross-sectional studies comparing immune parameters between age groups by new research that would measure the effects of healthy aging on vaccine effectiveness.
