Robust Antibody Responses in 70-80 Year Olds following 1 or 2 Doses of Pfizer COVID-19 Vaccine

Following the UK’s approach to extend the COVID vaccination interval from 3-4 weeks to 12 weeks, there was considerable international debate about the optimal approach for vaccine deployment in countries experiencing surges in cases and pressures on health service utilisation. We found that adults aged ≥70 years mount robust antibody responses after a single dose of the Pfizer BioNtech vaccine, with significantly higher antibody concentrations in previously-infected vaccinees. Two doses of Pfizer BioNtech vaccine produced very high S-antibody levels across all age-groups, with significantly higher antibodies in those with prior SARS-CoV-2 infection. Antibody levels were significantly higher after two doses of vaccine in those aged 70 years and above when compared with convalescent sera from clinically mild to moderate PCR confirmed cases. Our findings provide additional support for the UK approach of prioritising the first dose of vaccine.