Table 1.

Early attack rate, relative risk and incubation period by quantity of oysters consumed during lunch in the nursing home, France, January 2012

	Total	No. of cases	AR	RR	(95% CI)	Time of incubation (hours)
						Median	(IQR)
No. of oysters consumed
0	34	7	21%	1		43	(34–49)
3–4	40	18	45%	2·2	(1·0–4·6)	38	(31–44)
5–12	34	23	68%	3·3	(1·6–6·6)	38	(32–43)

AR, Attack rate; RR, relative risk; CI, confidence interval; IQR, interquartile range.

Test for trend: P < 0·001.