Table 4.

Indicators of international collaboration

	“Live-pathogen” research			“Non-pathogen” research
	1997–2001	2003–2007	Change	1997–2001	2003–2007	Change
Fraction of papers involving at least one US and one non-US institution
B. anthracis	16%	20%	22%	21%	11%	−48%**
Ebola virus	23%	38%	63%*	50%	36%	−29%
K. pneumoniae	26%	33%	25%*	24%	53%	124%**
Share of degree centrality of all non-US institutions
B. anthracis	18%	26%	44%	26%	26%	0%
Ebola virus	32%	28%	−13%	24%	39%	63%
K. pneumoniae	37%	39%	6%	NS	50	NS
Share of papers involving exclusively US collaborations
B. anthracis	39%	57%	46%*	25%	40%	62%***
Ebola virus	42%	44%	4%	45%	29%	−37%
K. pneumoniae	30%	30%	−1%	21%	5%	−74%†

NS, indicates an insufficient number of institutions to calculate share of degree centrality. *P ≤ 0.10, **P ≤ 0.05, ***P ≤ 0.01.

^†Significance test impossible due to small sample size.