Age-related heterogeneity in Neutralising antibody responses to SARS-CoV-2 following BNT162b2 vaccination

Collier, D.; Ferreira, I.; Datir, R.; Meng, B.; Bergamaschi, L.; The CITIID-NIHR Bioresource COVID-19 Collaboration,; Elmer, A.; Kingston, N.; Graves, B.; Smith, K. G.; Bradley, J.; Lyons, P.; Ceron-Gutierrez, L.; Barcenas-Morales, G.; Doffinger, R.; Wills, M.; Gupta, R. K.

Vaccines remain the cornerstone for containing the SARS-CoV-2 pandemic. mRNA vaccines provide protection in clinical trials using a two-dose approach, separated by a three-week gap. Here we assessed real world immune responses following vaccination with mRNA-based vaccine BNT162b2. Following the first and second doses of the BNT162b2 vaccine, we measured IFNgamma; T cell responses, both total IgG Spike, IgG Spike RBD and neutralising antibody responses to Spike in sera using a lentiviral pseudotyping system. Median age was 82 amongst 26 participants. Three weeks after the first dose a lower proportion of participants over 80 years old achieved adequate neutralisation titre of >1:4 for 50% neutralisation as compared to those under 80 (8/15 versus 11/11, p<0.05). Mean neutralisation titres in this age group after the first dose were lower than in younger individuals (p<0.05). Following the second dose, neutralising antibody response 50% titres were above 1:4 in all individuals and there was no longer a difference by age grouping. A significant proportion of individuals over 80 appear to require a second dose of vaccine, given in this study at three weeks, to achieve virus neutralisation.