Fig. 2: VACV-reactive and MPXV-neutralizing antibodies after Imvanex or MVA-H5 vaccination.

a–c, Detection of poxvirus-specific antibodies in a panel of n = 56 sera obtained from n = 18 Imvanex-vaccinated participants. Sera were obtained pre-vaccination and at three timepoints post-vaccination from individuals born before or during 1974 (triangles) or after 1974 (circles). a, Detection of VACV-reactive antibodies by ELISA with VACV-Elstree-infected cell lysate. Gray symbols are data points, the colored symbols and line reflect the geometric mean. b, Detection of MVA-neutralizing antibodies by PRNT in a serum selection of n = 33 sera. Gray symbols are data points; the colored symbols and line reflect the geometric mean. c, Detection of MPXV-neutralizing antibodies by PRNT on a serum selection of n = 33 sera. Graey symbols are data points; the colored symbols and line reflect the geometric mean. d, Detection of VACV-reactive antibodies by ELISA with VACV Elstree-infected cell lysate. A total of n = 86 sera were obtained from n = 22 participants in an MVA-H5 vaccination trial who received either a high (10⁸) or low (10⁷) dose regimen, with two (left) or three (right) vaccinations. Vaccination regimens are indicated in the legend above the panel. Gray symbols are data points; the colored symbols and line reflect the geometric mean. Fold differences between geometric mean titers after the second or booster vaccination with 10⁸ or 10⁷ PFU are indicated. e, Detection of MVA-neutralizing antibodies by PRNT in a serum selection of n = 42 sera obtained at V2 or V3. Lines indicate geometric mean; whiskers indicate 95% confidence interval. Fold differences between geometric mean titers after the booster vaccination are indicated. f, Detection of MPXV-neutralizing antibodies by PRNT, similar to e. 30% endpoint ELISA titers were calculated based on a five-fold dilution series, after subtraction of OD₄₅₀ values against a mock-infected cell lysate and relative to a positive control. The PRNT₅₀ titer was calculated on the basis of a two-fold dilution series relative to an infection control. A Mann–Whitney U-test was performed to compare VACV-reactive endpoint titers at V2 and V3 in d (two-tailed P = 0.05 considered significant). wk, weeks.