Factors Influencing the COVID-19 Vaccine Immune Response According to Age and Presence or Not of a Past History of COVID-19

Overview

Age is the main risk factor associated with the severity of COVID-19. From the beginning of the vaccination campaign, elderly subjects are part of the priority population. However, immunosenescence appears to play a role in the natural post-COVID-19 immunity of convalescent elderly subjects and also in the post-vaccination response. However, vaccination recommendations for both naïve (2 doses of vaccine) and convalescent subjects (1 dose of vaccine) do not differ according to age. To date, there is little data to suggest that the response to the vaccine in naïve or convalescent subjects may vary according to age in terms of qualitative and quantitative response and duration.

In addition, the reactogenicity following the vaccine, remains important with COVID-19 vaccines, whether using an Messenger RiboNucleic Acid (mRNA) technique or an adenovirus vector technique. A better understanding of the parameters of early inflammatory response explaining this reactogenicity would allow to optimize the formulation of future vaccines. There are still several unknowns concerning the post-vaccination immune response (immunogenicity and reactogenicity) in older subjects,depending on their history of COVID-19 and the type of vaccine administered. A better understanding of this immune response is necessary in order to propose the best vaccine strategies and regimens in this high-risk COVID-19 population. Thus, in partnership with Sanofi Pasteur and Bioaster, the Group On Mucosal Immunity And Pathogens (GIMAP) and Circulating Immune Complexes (CIC) vaccinology team proposes to conduct a study comparing the humoral, cellular, mucosal and reactogenic post-vaccination immune response in subjects with a history of COVID-19 \>3 months ago (convalescent, 1 dose of vaccine) versus subjects with no history of COVID-19 (naive, 1 or 2 doses of vaccine depending on the type of vaccine used) according to age.