Wild-type SARS-CoV-2 RBD-specific IgG antibodies
The GMTs of wild-type SARS-CoV-2 RBD-specific IgG antibodies in the low-dose and high-dose aerosolised Ad5-nCoV groups were 5210.84 (95% CI 3797.85, 7149.54), 5743.39 (95% CI 4059.90, 8124.94) at day 28, 3646.17 (95% CI 2706.95, 4911.28), 3328.55 (95% CI 2429.74, 4559.84) at month 3, 2711.25 (95% CI 2040.90, 3601.79), 2218.17 (95% CI 1621.50, 3034.39) at month 6, 1806.39 (95% CI 1363.49, 2393.14), 1452.29 (95% CI 1062.17, 1985.69) at month 12. Compared with the peaking RBD-specific IgG at day 28 after the booster dose, the GMTs of RBD-specific IgG antibodies in the low-dose and high-dose aerosolised Ad5-nCoV groups decreased by 30.30% and 42.05% at month 3, 47.97% and 61.38% at month 6, 65.33% and 74.71% at month 12, respectively. Likewise, in the CoronaVac group, the NAb GMTs decreased by 52.80%, 74.59% and 75.25%, respectively, at the same time points. However, the GMTs of the low-dose and high-dose aerosolised Ad5-nCoV groups were 26.25 and 23.98 folds higher at month 3, 36.23 and 29.67 folds higher at month 6, 24.81 and 19.96 folds higher at month 12, as compared with those of the CoronaVac group respectively (Wild-type SARS-CoV-2 RBD-specific IgG antibodies after a booster vaccination. Horizontal bars show GMTs and error bars show 95% confidence intervals. Data (folds) above the bars are the NAb GMT ratios of the homologous boost group to the heterologous boost group. Long lines connecting the GMTs of adjacent groups indicate trends in RBD-IgG antibodies over days after a booster vaccination. Data (%) above the bars show the percent reduction in GMTs of RBD-IgG antibody titres at day 90, day 180 and day 360 post-boost compared to day 28. All horizontal dotted lines denote the detectable cutoff titres of 1:10. GMT = geometric mean titre in serum. RBD-IgG = receptor-binding domain (RBD)-specific IgG antibodies.GMFIs of the low-dose and high-dose aerosolised Ad5-nCoV groups were significantly higher compared with that of the CoronaVac group throughout the time points till month 12 (Table S4).