TABLE 2.

Attack rate, community attack rate, and secondary attack rate for seasons and influenza virus with at least one case

Influenza virus	Season	Attack rate % (95% CIc)	Community attack rate % (95% CIb)	Secondary attack rate${}^{\mathrm{a}}$ % (95% CIb)	Relative attack rate${}^{\mathrm{a}}$ RR (95% CIb)
A (H1)	2013‐2014	1.7 (1.1, 2.7)	1.5 (0.9, 2.3)	2.3 (0.3, 7.7)	2.6 (1.2, 6.8)
A (H3)	2013‐2014	0.7 (0.4, 1.5)	0.6 (0.3, 1.2)	0.2 (0.0, 6.8)	1.3 (1.0, 13.3)
A (H3)	2014‐2015	3.7 (2.7, 5.0)	2.7 (1.8, 3.8)	7.6 (3.7 13.3)	3.8 (2.2, 6.5)
B	2013‐2014	2.0 (1.3, 3.0)	1.5 (0.9, 2.4)	5.3 (1.5, 12.7)	4.5 (1.9, 10.9)
B	2014‐2015	0.4 (1.3, 3.0)	0.3 (0.1, 0.7)	0.3 (0.0, 14.3)	2.3 (1.0, 78.9)

Note: The relative attack rate is the attack rate of influenza in households with a single case relative to the attack rate of influenza in households with no cases.

${}^{\mathrm{a}}$ Computed for the average household size.

${}^{\mathrm{b}}$ Credible interval.

${}^{\mathrm{c}}$ Confidence interval.