Contributing to research themes:
Objectives: To assess the relative immunogenicity of standard or extended interval BNT162b2 vaccination.
Design: Population based cohort study comparing immune responses 2 weeks after the second vaccine, with appropriate time-matched samples in participants who received standard or extended interval double vaccination.
Setting: Primary care networks, Birmingham, UK. December 2020 to April 2021.
Participants: 175 people aged over 80 years of age. All donors received the BNT162b2 Pfizer/BioNTech vaccination and were vaccinated with either a standard 3 week interval between doses or an extended interval schedule.
Main outcome measures: Peak quantitative spike-specific antibody and cellular immune responses.
Results: In donors without evidence of previous infection the peak antibody response was 3.5-fold higher in donors who had undergone delayed interval vaccination. Cellular immune responses were 3.6-fold lower.
Conclusion: Peak antibody responses after the second BNT162b2 vaccine are markedly enhanced in older people when this is delayed to 12 weeks although cellular responses are lower. Extended interval vaccination may therefore offer the potential to enhance and extend humoral immunity. Further follow up is now required to assess long term immunity and clinical protection.