Influenza and Bacterial Pathogen Coinfections in the 20th Century

Table 3

Comparison of coinfection with major bacterial pathogens and influenza by pandemic period (𝑛=56)^{a, b}.

Bacteria	Pandemic period	Studies (𝑛)	Estimates from random effects model
			Average % coinfection with influenza virus	95% Confidence interval
S. pneumoniae	1918	23	56.5	45.6–66.8
	1957	9	15.6	8.8–26.0
	1968	3	27.8	2.9–83.2
H. influenzae	1918	17	17.9	9.9–30.3
	1957	9	6.9	4.5–10.5
	1968	1	6.3^c	—
Streptococcus spp.	1918	20	21.7	12.9–34.1
	1957	6	4.6	0.6–28.2
	1968	1	9.4^c	—
Staphylococcus spp.	1918	12	18.8	8.0–38.0
	1957	11	39.7	20.9–62.2
	1968	3	10.3	4.9–20.2

^aProportions for S. pneumoniae, H. influenzae, Streptococcus spp., and Staphylococcus spp. were different (𝑃<.0001, Kruskal-Wallis test; Bonferonni correction, 𝛼=0.025) during 1918-1919 pandemic.
^bProportions for S. pneumoniae, H. influenzae, Streptococcus spp., and Staphylococcus spp. were different (𝑃=.0006, Kruskal-Wallis test; Bonferonni correction, 𝛼=0.025) during 1957 pandemic.
^cOriginal data.