Table 2.

Pooled results of coinfecting bacterial pathogens identified with influenza virus during seasonal and pandemic influenza periods.

Bacteria	Transmission period	Studies (n)	Estimates from random effects model
			Average % coinfection with influenza virus	95% Confidence interval
S. pneumoniae	Seasonal	22	16.6a	7.9–31.6
	Pandemic	35	40.8	30.5–52.0
H. influenzae	Seasonal	10	5.2b	2.3–11.5
	Pandemic	27	12.9	8.3–19.5
Streptococcus spp.	Seasonal	7	1.8c	0.3–9.3
	Pandemic	27	15.7	9.1–25.8
Staphylococcus spp.	Seasonal	12	6.2d	2.3–15.7
	Pandemic	26	25.0	15.4–37.8

^aSeasonal versus pandemic pooled average proportion of patients with S. pneumoniae coinfection (P = .008, Kruskal-Wallis test; Bonferonni correction, α = 0.008).

^bSeasonal versus pandemic pooled average proportion of patients with H. influenzae coinfection (P = .02, Kruskal-Wallis test; Bonferonni correction, α = 0.008).

^cSeasonal versus pandemic pooled average proportion of patients with Streptococcus spp. coinfection (P = .009, Kruskal-Wallis test; Bonferonni correction, α = 0.008).

^dSeasonal versus pandemic pooled average proportion of patients with Staphylococcus spp. coinfection (P = .005, Kruskal-Wallis test; Bonferonni correction, α = 0.008).

^eDuring seasonal flu period, the proportions of coinfection caused by S. pneumoniae, H. influenzae, Streptococcus spp., and Staphylococcus spp. were different. (P = .009, Kruskal-Wallis test; Bonferonni correction, α = 0.008).

^fDuring pandemic flu period, the proportions of coinfection caused by S. pneumoniae, H. influenzae, Streptococcus spp., and Staphylococcus spp. were different. (P < .0001, Kruskal-Wallis test; Bonferonni correction, α = 0.008).