Antibody and T cell memory immune response after two doses of the BNT162b2 mRNA vaccine in older adults with and without prior SARS-CoV-2 infection

Demaret, Julie; Corroyer-Simovic, Bénédicte; Alidjinou, Enagnon Kazali; Goffard, Anne; Trauet, Jacques; Miczek, Sophie; Vuotto, Fanny; Dendooven, Arnaud; Huvent-Grelle, Dominique; Podvin, Juliette; Dreuil, Daniel; Faure, Karine; Deplanque, Dominique; Bocket, Laurence; Duhamel, Alain; Labreuche, Julien; Sobaszek, Annie; Puisieux, Francois; Labalette, Myriam; Lefèvre, Guillaume

We quantified S1-specific IgG, neutralizing antibody titers, specific IFNγ secreting T cells and functionality of specific CD4+ and CD8+ T cells in 130 young adults (median age 44.0 years) and 106 older residents living in a long-term care facility (86.5 years) after 2 doses of BNT162b2. Three months after the first injection, humoral and cellular memory responses were dramatically impaired in the 54 COVID-19-naive older compared to the 121 COVID-19-naive younger adults. Notably, older participants’ neutralizing antibodies, detected in 76.5% (versus 100% in young adults, P < 0.0001), were ten times lower than the younger’s antibody titers (P < 0.0001). Antibody and T cell responses were greater among the 52 COVID-19-recovered than among the 54 COVID-19-naive older adults (P < 0.0001). Our study shows that 2 doses of BNT162b2 does not guarantee long-term protection against SARS-CoV-2 in the older. An additional dose should be considered to boost their specific memory response.