Variation in hepatitis B immunization coverage rates associated with provider practices after the temporary suspension of the birth dose

Table 2 Typical age(s) at receipt of hepatitis B vaccine doses and change in % underimmunized at 24 months for the hepatitis B vaccine series, baseline vs. birth dose suspension cohorts, children enrolled in five large U.S. provider groups, October 1996 – December 1999

	Modal Age in Months at Hepatitis B Vaccination*
Group	Exposure cohort	Dose 1	Dose 2	Dose 3	Predicted Absolute Change in % Underimmunized at 24 Months in the Suspension vs. Baseline Period^†	OR for Being Underimmunized at 24 Months in the Suspension vs. Baseline Period (95% CI)^§
A	Baseline:	≤2	3–4	11–12	-2%	0.7 (0.4 – 1.3)
	Suspension:	≤2	3–4	11–12
B	Baseline:	≤2	≤2	17–18	-5%^‡	0.5 (0.2 – 0.9)
	Suspension:	≤2	3–4	11–12
C	Baseline:	Birth	≤2	5–6	-3%^‡	0.8 (0.7 – 0.9)
	Suspension:	≤2	3–4	5–6
D	Baseline:	Birth	≤2	9–10	+6%^‡	2.7 (1.7 – 4.4)
	Suspension:	5–6	9–10	15–16
E	Baseline:	Birth	≤2	5–6	+9%^‡	3.1 (2.3 – 4.2)
	Suspension:	5–6	9–10	11–12

*Baseline cohort: Born between October 1996 – June 1999 (n = 67,835). Birth dose suspension cohort: Born between July – September 1999 (n = 6,401). Age at vaccination was grouped into the following categories: birth (0–7 days), ≤ 2 months (8 days – 2 months), 3–4 months, 5–6 months, 7–8 months, 9–10 months, 11–12 months, 13–14 months, 15–16 months, 17–18 months, 19–20 months, 21–24 months, and did not receive dose by 24 months. For each dose, the most common ages at vaccination were listed.
^† For each provider group, the predicted absolute difference was calculated comparing the % hepatitis B underimmunized at age 24 months among the July 1999 birth cohort as fitted from multivariate regression models adjusting for temporal trend versus the % underimmunized as extrapolated from baseline (i.e., absolute difference = [fitted % underimmunized]_July1999 - [predicted % underimmunized]_July1999).
^‡ p < 0.05.
^§ ORs are from logistic regression models adjusted for temporal trend.

ISSN: 1471-2431