BNT162b2 Vaccination in People Over 80 Years of Age Induces Strong Humoral Immune Responses with Cross Neutralisation of P.1 Brazilian Variant

Background: Age is the major risk factor for mortality after SARS-CoV-2 infection and older people have received priority consideration for COVID-19 vaccination. However vaccine responses are often suboptimal in this age group and few people over the age of 80 years were included in vaccine registration trials. Methods: We determined the serological and cellular response to spike protein in 100 people aged 80-96 years at 2 weeks after second vaccination with the Pfizer BNT162b2 mRNA vaccine. Findings: Antibody responses were seen in every donor with high titres in 98%. Spike-specific cellular immune responses were detectable in only 63% and correlated with humoral response. Previous SARS-CoV-2 infection substantially increased antibody responses after one vaccine and antibody and cellular responses remained 28-fold and 3-fold higher respectively after dual vaccination. Post-vaccine sera mediated strong neutralisation of live Victoria (Wuhan-like prototype) infection and although neutralisation titres were reduced 14-fold against the P.1 variant first discovered in Brazil they remained largely effective. Interpretation: These data demonstrate that the mRNA vaccine platform delivers strong humoral immunity in people up to 96 years of age and retains broad efficacy against the P.1 Variant of Concern. Funding: This work was supported by the UK Coronavirus Immunology Consortium (UK-CIC) funded by DHSC/UKRI and the National Core Studies Immunity programme. Declaration of Interest: None to declare. Ethical Approval: The work was performed under the CIA UPH IRAS approval (REC 20\NW\0240) and conducted according to the Declaration of Helsinki and good clinical practice.