Figure 2.

Omicron Spike recognition and neutralization with plasma from naive individuals who received a short versus a long mRNA vaccine dose interval

(A) SARS-CoV-2 vaccine cohort design.

(B) 293T cells were transfected with the full-length Spike from different SARS-CoV-2 variants (D614G, Beta, Delta, and Omicron) and stained with the CV3-25 Ab or with plasma from naive donors who received a short (4 weeks, yellow) or long (16 weeks, red) interval between doses collected 3 weeks after the second dose (V3) and analyzed by flow cytometry. The values represent the MFI normalized by CV3-25 Ab binding and presented as percentages of CV3-25 binding.

(C) Neutralizing activity was measured by incubating pseudoviruses bearing indicated SARS-CoV-2 Spikes (D614G, Beta, Delta, and Omicron), with serial dilutions of plasma for 1 h at 37°C before infecting 293T-ACE2 cells. Neutralization half-maximal inhibitory serum dilution (ID₅₀) values were determined using a normalized non-linear regression using GraphPad Prism software. Undetectable measures are represented as white symbols, and limits of detection are plotted. Error bars indicate means ± SEM. For naive donors vaccinated with the short interval, n = 19. For naive donors vaccinated with the long interval, n = 25. Each symbol/points identifies one donor. Statistical significance was tested using a Mann-Whitney test (^∗p < 0.05; ^∗∗p < 0.01; ^∗∗∗p < 0.001; ^∗∗∗∗p < 0.0001).