Table 3.

Population Size and Exclusions.

OHP children in ALERT:	20,411
Exclusions (in order applied)
Not born in Oregon	1,004
<180 days of enrollment by age 2	1,123
<365 days of enrollment by age 2	583
Not enrolled within 30 days of birth	345
Not enrolled after 1 year of age	2,884
Not enrolled through 15–18-month period	1,009
No immunizations reported post birth	264
Total exclusions	7,212
Total study population	13,199

OHP is the Oregon Health Plan ALERT is the ALERT Immunization Information System.