Table 3.

Seroconversion Rates and Geometric Median Units (GMU) of Circulating Antibodies Against SARS-CoV-2 Proteins

Antibodies Detected	Group	Indicators	Second Dose	Second Dose + 2 wk	Second Dose + 4 wk
Anti-S1-RBD IgG (WHO A.U./mL)	Total vaccine	Seroconversion n/N	23/72	54/72	57/72
		(%)	(31.94)	(75.00)	(79.17)
		GMU	19.60	76.50	72.43
		(95% CI)	(15.24–25.22)	(57.67–101.5)	(56.96–92.11)
	18–59 years	Seroconversion n/N	18/45	37/45	38/45
		(%)	(40.00)	(82.22)	(84.44)
		GMU	25.33	103.33	99.40
		(95% CI)	(19.07–33.64)	(75.31–141.8)	(74.53–132.6)
	≥ 60 years	Seroconversion n/N	5/27	17/27	19/27
		(%)	(18.52)	(62.96)	(70.37)
		GMU	12.67	45.84	42.24
		(95% CI)	(08.03–19.99)	(27.51–76.36)	(29.44–60.61)
	Placebo	Seroconversion n/N	0/12	0/9	0/0
		(%)	(0)	(0)	N/D
		GMU	10.43	6.19	N/D
		(95% CI)	(04.33–25.10)	(01.85–20.76)	N/D
Anti-N IgG (WHO A.U./mL)	Total vaccine	Seroconversion n/N	2/72	5/72	7/72
		(%)	(2.78)	(6.94)	(9.72)
		GMU	10.77	12.66	14.4
		(95% CI)	(07.95–14.57)	(09.36–17.12)	(10.89–19.04)
	18–59 years	Seroconversion n/N	2/45	5/45	6/45
		(%)	(4.44)	(11.11)	(13.33)
		GMU	10.25	12.11	13.51
		(95% CI)	(06.97–15.08)	(08.07–18.16)	(09.21–19.81)
	≥ 60 years	Seroconversion n/N	0/27	0/27	1/27
		(%)	(0)	(0)	(3.70)
		GMU	11.70	13.70	16.05
		(95% CI)	(06.96–19.67)	(08.60–21.82)	(10.65–24.18)
	Placebo	Seroconversion n/N	1/12	0/10	0/0
		(%)	(8.3)	(0)	(-)
		GMU	11.06	9.61	N/D
		(95% CI)	(04.03–30.35)	(02.90–31.90)	(-)

Timepoints refer to the number of days after the first dose of vaccine or placebo in the schedule.

Abbreviations: A.U., arbitrary unit; CI, confidence interval; GMU, geometric median unit; IgG, immunoglobulin G; N, nucleoprotein; N/D, not determined; RBD, receptor binding domain; S, Spike protein; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; WHO, World Health Organization.