Fig. 1.
Change in number of children aged under 5 years hospitalized with invasive pneumococcal disease (IPD) from 1998–1999 to 2006a recorded by sentinel surveillance systems,b by number of cases in 1998 and 1999, Tennessee, United States of America
PCV7, seven-valent pneumococcal conjugate vaccine.
a PCV7 was introduced in the United States in 2000.
b Each sentinel system comprised either a single hospital with at least one hospitalized IPD case in either 1998 or 1999 or a group of hospitals, in which each hospital had at least five cases during 1998 and 1999 combined.
c A case was a child aged under 5 years who was hospitalized with IPD caused by any Streptococcus pneumoniae serotype.
d The change in the number of IPD cases recorded by the sentinel surveillance system was judged to be in agreement with the change observed in the corresponding surveillance area when the magnitude of the change in number recorded by the surveillance system fell within the 95% confidence interval of the magnitude of the change in the incidence of hospitalized IPD cases for the corresponding surveillance area.
e The whole surveillance area was the area covered by the Active Bacterial Core surveillance system in the United States in which all the sentinel surveillance systems were located; here the area included five counties in Tennessee.
Note: The vertical line indicates the change in the incidence of hospitalized IPD cases recorded in the whole surveillance area.
