Antibody persistence and safety after heterologous boosting with orally aerosolised Ad5-nCoV in individuals primed with two-dose CoronaVac previously: 12-month analyses of a randomized controlled trial

Figures & data

Figure 1. Study profile. Ad5-nCoV = orally administered aerosolised adenovirus type-5 vector-based COVID-19 vaccine carrying full-length SARS-CoV-2 spike gene. CoronaVac = intramuscularly administered inactivated whole-virion SARS-CoV-2 vaccine.

Figure 2. NAbs against live wild-type SARS-CoV-2 and omicron BA.1 subvariant 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 NAbs over days after a booster vaccination. Data (%) above the bars show the percent reduction in GMTs of NAb titres at day 90, day 180 and day 360 post-boost compared to day 28. All horizontal dotted lines denote the cutoff levels for positivity (1:8) or the levels of WHO international standard (NIBSC code 20/136). Data below the cutoff level were assigned half the limit. GMT = geometric mean titre in serum. NAb = neutralizing antibody.

Figure 3. Neutralizing antibodies against omicron BA.4/5 pseudovirus 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 neutralizing antibodies over days after a booster vaccination. Data (%) above the bars show the percent reduction in GMTs of NAb titres at day 90, day 180 and day 360 post-boost compared to day 28. All horizontal dotted lines denote the cutoff levels for positivity (1:30). Data below the cutoff level were assigned half the limit. GMT = geometric mean titre in serum. NAb = neutralizing antibody.

Table 1. GMT, seropositivity rate, and GMT ratio of neutralizing antibodies to omicron BA.4/5 subvariant pseudovirus after a booster vaccination.

	Low-dose group (n = 40)	p Value*	High-dose group (n = 40)	p Value**	CoronaVac group (n = 40)	p Value***
Day 28
GMT	149.58 (101.03, 221.45)	<0.0001	158.52 (111.36, 225.66)	<0.0001	23.75 (19.41, 29.05)	0.8247
Seropositivity	92.50 (79.61, 98.43)	<0.0001	94.87 (82.68, 99.37)	<0.0001	40.00 (24.86, 56.67)	1.0000
GMT ratio	6.30 (4.60, 9.98)	–	6.68 (4.87, 10.60)	–	ref	–
Month 3
GMT	117.47 (83.65, 164.96)	<0.0001	112.53 (83.77, 151.16)	<0.0001	23.13 (17.05, 31.38)	0.8478
Seropositivity	90.00 (76.34, 97.21)	<0.0001	97.37 (86.19, 99.93)	<0.0001	30.00 (16.56, 46.53)	0.1842
GMT ratio	5.08 (3.72, 8.00)	–	4.86 (3.57, 7.64)	–	ref	–
Month 6
GMT	65.50 (48.31, 88.81)	<0.0001	56.80 (41.65, 77.46)	<0.0001	16.18 (14.78, 17.70)	0.5084
Seropositivity	84.21 (68.75, 93.98)	<0.0001	81.08 (64.84, 92.04)	<0.0001	7.69 (1.62, 20.87)	0.7204
GMT ratio	4.05 (2.84, 7.01)	–	3.51 (2.49, 5.97)	–	ref	–
Month 12
GMT	40.97 (30.15, 55.67)	0.0038	35.08 (26.31, 46.77)	0.0100	17.79 (13.83, 22.88)	0.4582
Seropositivity	62.50 (45.80, 77.27)	0.0032	55.26 (38.30, 71.38)	0.0126	15.38 (1.92, 45.45)	0.5160
GMT ratio	2.30 (1.71, 3.54)	–	1.97 (1.49, 2.93)	–	ref	–

Notes: Data are GMT (95% CI), seropositivity (%, 95% CI), GMT ratio (95% CI). GMT = geometric mean titre. Seropositivity (%): The proportion of participants whose antibody titres was defined as a detectable neutralizing antibody titre ≥1:30. Data below the cutoff level were assigned half the limit. *The p values of this column are the results of comparison between low-dose aerosolised vaccine group and inactivated vaccine group. **The p values of this column are the results of comparison between high-dose aerosolised vaccine group and inactivated vaccine group. ***The p values of this column are the results of comparison between low-dose aerosolised vaccine group and high-dose aerosolised vaccine group. GMT ratio = heterologous boost group/homologous boost group. Measurements on day 28 were taken 28 days after the booster vaccination.

Figure 4. 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.