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

Abstract

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.

Convergent CDR3 homology amongst Spike-specific antibody responses in convalescent COVID-19 subjects receiving the BNT162b2 vaccine

“…This is consistent with prior studies identifying sharp increases in neutralizing antibody titres and Spike-specific IgG in double-dosed individuals, highlighting an induction of the memory response against the virus [ 2 , 3 ]. Notably, P1 – who received one dose of BNT162b2 at the time of sampling – displayed equal or greater antibody-specific responses compared to double-dosed P2, underscoring the potent existing immunological memory in convalescent individuals that has been repeatedly observed in similar studies [ [8] , [9] , [10] , [11] , [12] , [13] , [14] , [15] ].…”

“…The long-term immune response elicited following mRNA vaccination is similar to that of SARS-CoV-2 infection, with studies reporting strong circulating memory B cell responses after two consecutive doses [ 7 ]. For convalescent COVID-19 subjects, strong Spike-specific and neutralizing antibody responses appear rapidly following the initial mRNA vaccine dose, with several studies suggesting that additional booster doses may have limited immunological benefit in this subject population [ [8] , [9] , [10] , [11] , [12] , [13] , [14] , [15] ]. This expediated protective immunity likely stems from the pre-existent SARS-CoV-2-specific B cell memory responses present in these individuals that may be driven by germinal centre formation, which produces high affinity, long-lasting memory B cells able to secrete virus-neutralizing antibodies [ 4 , 16 ].…”