Table 4.

Anti-spike immunoglobulin G concentrations determined by enzyme-linked immunosorbent assay over time.

	Naïve for COVID-19 (Seronegative) (n=27)	Status after COVID-19 (Seropositive) (n=14)	p-value
Anti-Spike IgG (day 0), RU/mL	<8•0 (0)	31.8 (15•1–66•7)	<0•0001
Anti-Spike IgG (day 21), RU/mL	81•8 (46•6–143•4)	854•0 (611•5–1192•7)	<0•0001
Anti-Spike IgG (day 49), RU/mL	619•7 (454•9–844•3)	1061•8 (696•1–1619•5)	<0•0001

Data are geometric mean (95% CI). Statistical difference is calculated using a mixed effects linear regression model adjusted for sex with posthoc estimated marginal mean contrasts. IgG=immunoglobulin. RU=reference units.