Sharing some real world data on antibody responses to the Pfizer mRNA vaccine. We tested serum from 23 participants (median age 82) vaccinated with the first dose 3 weeks previously.
Serum IgG antibodies against Spike were measured with a luminex assay. Virus neutralisation by participant serum was measured with a virus pseudotyping system where virus particles are made that express the SARS-CoV-2 Spike protein. The figure shows that the two were correlated. 
All participants under 80 (n=8) demonstrated reasonable neutralisation titres against wild type virus (D614G). However, 7/15 of those above 80 failed to neutralise virus to 50%. In blue and purple are participants who neutralised virus. In grey is a participant that did not.
This last figure summarises the data. We should be able to report the findings for the B.1.1.7 virus early next week. We need to see whether the second dose will generate responses in these seven individuals whose responses after first dose were suboptima/absent.
This is important because we need to know whether vaccinees are indeed protected, and data in older persons are lacking. Huge thanks to the team, including CUH Occ health, NIHR Bioresource @damicollier @rpdatir @CambridgeBRC @CUH_NHS
should add that the neutralisation data were done twice and independently with each dot representing the mean of the two experiments for each participant
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