Figure 2

Neutralizing responses induced by SARS-CoV-2 mono- and bivalent inactivated vaccines in mice. (a) Mice were immunized three times with monovalent I-P60 (n = 4) or I-BA.1 (n = 4), bivalent I-P60/BA.1 (n = 4), or Ovalbumin (OVA) (n = 4) on day 0, 21, and 42, and serum was sampled on day 0, 14, 37, and 56. (b) Neutralization of homologous and heterologous viruses by serum was analyzed (left and right graphs for each group, respectively). In vaccines containing I-P60, original-D614G virus was used as the homologous virus in this assay. Dots represent values from individual animals, bars represent group means. < indicates that at least one value used to calculate the mean is below LLOQ; the LLOQ was determined as the first dilution tested in the assay, 1:12.5. Statistical analysis was only carried out between groups where all values were above the LLOQ. A Kruskal–Wallis test was done to compare more than two groups with the post-hoc Dunn’s multiple comparisons test (I-P60, I-P60/BA.1, and I-BA.1 serum from day 56 against BA.1). A Mann–Whitney test was used to compare two groups (at each timepoint, ID₅₀ values against each virus were compared for the inactivated vaccine groups). None of the tests showed significant differences. ID₅₀ values were calculated based on curves shown in Supplementary Fig. S3. ID₅₀, 50% inhibitory dilution. LLOQ, lower limit of quantification.