Table 2.

Geometric mean ratio of anti-SARS-CoV-2 spike protein RBD antibodies 2 weeks after ChAdOx1/AZD1222 vaccination among participants who previously received two doses of CoronaVac.

Group	N	Geometric mean concentration (95% CI) (BAU/mL)	Geometric mean ratio (95% CI)
IM	41	6414.62 (5107.56–8056.17)	Ref.
ID1	40	5669.49 (4560.30–7048.45)	0.94 (0.80–1.09)
ID2	43	8,230.37 (6,697.04-10,114.8)	1.28 (0.95-1.74)

SARS-CoV-2, severe acute respiratory syndrome coronavirus-2; RBD, receptor-binding domain; CI, confidence interval; IM, intramuscular standard dose; ID1, 20% intradermal fractional dose; ID2, 40% intradermal fractional dose.