Further data on immune responses following the Pfizer mRNA vaccine against pseudo virus bearing Spike protein with mutations in the B.1.1.7 variant (del69/70, del 144/145, N501Y, A570D, P681H, T716I, S982A, D1118H). There is a modest reduction in efficacy of vaccine sera.

Among 15 individuals with neutralisation activity three weeks after the Pfizer mRNA vaccine, 10 showed evidence of reduction in efficacy of antibodies against the B.1.1.7 mutant (Fold change >3). The highest fold change was 6. Median fold change was 3.85 (IQR 2.68-5.28).

These modest changes are what we expected to see given the mutational profiles, esp del 144/145 which is a target region for our antibodies. Vaccines should be highly effective and vaccine coverage is a priority. Full results and methods on Medrxiv in the coming days.