Table 4.

Seropositivity Rates and GMTs of Circulating Neutralizing Antibodies Against SARS-CoV-2 Proteins

Antibodies Detected	Group	Indicators	Second Dose + 2 wk	Second Dose + 4 wk
Surrogate virus neutralization	Total vaccine	Seropositivity n/N	63/72	59/72
		(%)	(87.5)	(81.94)
		GMT	14.23	15.54
		(95% CI)	(10.54–19.21)	(11.23–21.51)
	18–59 y	Seropositivity n/N	44/45	39/45
		(%)	(97.78)	(86.67)
		GMT	20.78	18.95
		(95% CI)	(14.81–29.18)	(12.87–27.92)
	≥ 60 y	Seropositivity n/N	19/27	20/27
		(%)	(70.37)	(74.07)
		GMT	8.21	11.75
		(95% CI)	(04.83–13.94)	(06.55–21.12)
	Placebo	Seropositivity n/N	0/11	N/D
		(%)	(0)	(-)
		GMT	0	N/D
		(95% CI)	(0)	(-)
Pseudotyped virus neutralization	Total vaccine	Seropositivity n/N	66/69	66/69
		(%)	(95.65)	(95.65)
		GMT	52.22	41.33
		(95% CI)	(35.12–77.65)	(29.10–56.69)
	18–59 y	Seropositivity n/N	44/45	44/45
		(%)	(97.78)	(97.78)
		GMT	83.74	59.37
		(95% CI)	(51.78–135.4)	(38.08–92.58)
	≥ 60 y	Seropositivity n/N	22/24	22/24
		(%)	(91.67)	(91.67)
		GMT	26.07	22.31
		(95% CI)	(14.91–45.59)	(13.39–37.18)
	Placebo	Seropositivity n/N	0/10	N/D
		(%)	(0)	(-)
		GMT	0	N/D
		(95%CI)	(0)	(-)
Conventional virus neutralization	Total vaccine	Seropositivity n/N	55/72	60/72
		(%)	(76.39)	(83.33)
		GMT	10.10	15.54
		(95% CI)	(7.28–14.01)	(22.18)
	18–59 y	Seropositivity n/N	36/45	38/45
		(%)	(80.0)	(84.44)
		GMT	10.60	14.81
		(95% CI)	(6.92–16.26)	(9.49–23.09)
	≥ 60 y	Seropositivity n/N	19/27	22/27
		(%)	(70.37)	(81.48)
		GMT	9.32	16.84
		(95% CI)	(5.43–15.99)	(8.95–31.67)
	Placebo	Seropositivity n/N	6/11	N/D
		(%)	(54.54)	(-)
		GMT	5.48	N/D
		(95% CI)	(1.84–16.29)	(-)

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

Abbreviations: CI, confidence interval; GMT, geometric mean titer; N, nucleoprotein; N/D, not determined; S, Spike protein; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.