Fig. 2

Neutralizing antibodies against the wild-type, Alpha, Beta, Delta, and Omicron variants. Plasma obtained from the study population before (2CoVac) and 4 weeks after boosting with ChAdOx-1(2CoVac + ChAd) (N = 24) or BNT162b2 (2CoVac + BNT) (N = 22) was used to determine the percent inhibition of neutralizing antibodies against the wild-type, Alpha, Beta, Delta, and Omicron variants. The horizontal lines indicate the 30% inhibition threshold of neutralizing antibodies. Dot plots represent each individual, lines connect data from the same individual on the NAbs against the indicated variants, and medians with interquartile ranges are shown. The numbers in parentheses indicate the median values. The Mann–Whitney U test was used to compare the different samples; * p < 0.05, ** p < 0.01, ns = not statistically significant. The Wilcoxon signed-rank test was used for comparisons of the paired samples; ^# p < 0.05, ^#### p < 0.0001