Fig. 4: Viral loads.

Calves (n = 7 to 9 biologically independent animals, see Table 1) received either a single or two doses (1D or 2D, respectively) of ChAd155-RSV vaccine or placebo, followed by a short (4 weeks) or long (16 weeks) duration of immunity (short DOI or long DOI, respectively), and then a bovine RSV challenge. Placebo-S and placebo-L groups indicate the control groups subjected to the short-DOI and long-DOI regimens, respectively (note that the sample size in the placebo-L group of Study 2 had decreased to n = 4 on day post-challenge 9; see Fig. 3). Virus loads of lung broncho-alveolar lavage (BAL) samples (a, c, e) and nasopharyngeal samples (b, d, f) are presented as geometric mean concentrations with 95% confidence intervals. Dotted lines (6.3 TCID₅₀/mL) represent the lower limit of detection (LOD). Negative samples were assigned a value of 1.995. Vaccine groups were compared by two-sided t tests with the respective control groups using ANOVA mixed models for repeated measurements. Significant differences are indicated by asterisks color-matched with the vaccine group indicated in the keys above the figure (**P ≤ 0.01; ***P ≤ 0.001). Source data and statistical analyses with exact P values are provided as a Source data and Supplementary Data 1 and 2, respectively.