Figure 1: ACE2 dependence and neutralization of the Omicron variant by Pfizer BNT162b2 elicited immunity.
(A) Images of infection foci in titration of live SARS-CoV-2 Omicron virus on H1299-ACE2 and H1299 parental cells. Numbers above well images denote viral stock dilution. Scale bar is 2mm. (B) Quantified number of foci as a function of Omicron virus stock dilution. Mean and standard deviation of 6 replicates from 2 independent experiments. (C) Neutralization of Omicron virus compared to D614G ancestral virus by plasma from participants vaccinated with BNT162b2 and previously SARS-CoV-2 infected (green) or vaccinated only (orange). Numbers in black above each virus strain are geometric mean titers (GMT) of the reciprocal plasma dilution (FRNT50) resulting in 50% reduction in the number of infection foci. Red horizontal line denotes most concentrated plasma used. 21 samples were tested from 19 participants in 2 independent experiments, where n=6 were vaccinated only and n=13 were vaccinated and previously infected. p=4.8 × 10−5 as determined by the Wilcoxon rank sum test. (D) Geometric means and 95% confidence intervals of fold-changes between participant FRNT50 values for ancestral D614G versus Omicron neutralization. Purple denotes all participants, green denotes vaccinated previously infected and orange denotes vaccinated only. (E) Prediction of vaccine efficacy against symptomatic infection (left) and severe disease (right) based on Omicron neutralization results.