Table 4.

Temporal changes in the positive rate for IgG antibodies.

		Positive rate n (%)
3 months ( n = 6 50)		505 (77.7%)
	Sex
	Women (n = 504)	382 (75.8%)
	Men (n = 146)	123 (84.3%)
	Age group (y)
	18–35 (n = 148)	115 (77.7%)
	36–55 (n = 322)	240 (74.5%)
	≥56 (n = 180)	150 (83.3%)
	Severity
	Asymptomatic, mild to moderate (n = 607)	471 (77.6%)
	Severe (n = 34)	26 (76.5%)
	Critical (n = 6)	6 (100%)
6 months (n = 648)		568 (87.7%)
	Sex
	Women (n = 504)	440 (87.3%)
	Men (n = 144)	128 (88.9%)
	Age group (y)
	18–35 (n = 130)	133 (86.9%)
	36–55 (n = 318)	276 (86.8%)
	≥56 (n = 200)	179 (89.5%)
	Severity
	Asymptomatic, mild to moderate (n = 585)	512 (87.5%)
	Severe (n = 48)	43 (89.6%)
	Critical (n = 9)	9 (100%)
9 months (n = 387)		345 (89.2%)
	Sex
	Women (n = 294)	259 (88.1%)
	Men (n = 93)	86 (92.5%)
	Age group (y)
	18–35 (n = 70)	60 (85.7%)
	36–55 (n = 195)	174 (89.2%)
	≥56 (n = 122)	111 (91.0%)
	Severity
	Asymptomatic, mild to moderate (n = 352)	314 (89.2%)
	Severe (n = 27)	23 (85.2%)
	Critical (n = 6)	6 (100%)