Rotavirus vaccine coverage among a 2010 birth cohort and risk factors for partial or no coverage, Washington State 2010

K. Stigi, C. DeBolt, K. Lofy Washington State Department of Health – Office of Communicable Disease Epidemiology

Discussion• Rotavirus vaccine coverage estimates for WA using IIS data higher than NIS coverage estimates

• Partial coverage known to confer substantial immunity, suggesting that 80.6% of 2010 birth cohort achieved some immunity despite only 60% achieving ‘full’ coverage

• Among those with no RV5 dose, nearly 40% received another vaccine between 6 - 15 weeks of age; unclear whether vaccine was not offered or refused

• Rotavirus unique vaccine in that first dose must be administered by 15 weeks of age, otherwise series not initiated

• Coverage estimates highly variable among WA counties

• The following maternal characteristics strongly associated with 'partial' coverage: younger age; AI/AN, Black, or Pacific Islander race; multiparity; ≤ high school education or some college (compared to ≥ college degree); Medicaid use

• The following maternal characteristics strongly associated with ‘No RV5’: AI/AN race; married; multiparity; some college

• Consistent with previously described risk factors for delayed or no vaccine coverage, multiparity significantly associated with 'partial' and 'no RV5' groups; odds increase with each previous live birth

• Further studies needed to better understand reasons for no rotavirus vaccine coverage

• < 100% of WA vaccine providers participate in the WA IIS

• Since IIS initially populated with birth certificate data, unclear whether those with no immunization data refused all vaccines, see a provider who does not participate in IIS, or left the state

• Inactive records lack ‘date effective’ for inactivity, therefore unclear whether these patients were active through rotavirus vaccine time period so they were excluded

Phyllis Reed1, Belinda Baker1, Janna Bardi1, Sherry Riddick2,Yousif Hozail2, Wayne Turnberg1, Natasha Close1, Kathryn MacDonald1, Tracy Sandifer1, Erica Smith3

1 Washington State Department of Health2 Washington State Immunization Information System3 Pennsylvania Department of Health

• National Immunization Survey (NIS) 2009 and 2010 estimates ranked WA State among lowest in nation for rotavirus coverage (20.9% and 50.4%, respectively)

• Prior to rotavirus vaccine introduction, one in 60 U.S. children were hospitalized for rotavirus by age 5

• Vaccines For Children Program (VFC) provides free vaccine to all children ≤ 18 years in WA State and distributes the RotaTeq (RV5) rotavirus vaccine

Recommended schedule for RV51

• WA State Immunization Information System (IIS) is a secure web-based registry with 95% participation among vaccine providers, covering 98% of VFC doses

• Studies have found partial RV5 vaccination confers up to 85% protection (range: 69% - 85%)2,3

2 Boom, et al. Effectiveness of Pentavalent Rotavirus Vaccine in a Large Urban Population in the United States, Pediatrics 2010. 3 Staat, et al. Effectiveness of Pentavalent Rotavirus Vaccine Against Severe Disease, Pediatrics 2011.

To estimate rotavirus vaccine coverage in WA State using IIS data, and to explore maternal characteristics associated with partial or no rotavirus coverage

Rotavirus Vaccine Coverage Estimates

• IIS data extracted for all children born during 2010 (n=97,664)

• Records with no immunization data excluded (5,000)

• Inactive records excluded (5,202)

• Coverage groups assigned:

Maternal Predictors For ‘Partial’ or ‘No’ Coverage

• IIS records linked to 2010 birth certificate data

• ‘No vaccine’ group excluded from analyses

• Dataset restricted to records with WA birth residence and complete data among variables of interest

• X2 tests assessed univariate associations (Table 1)

• Odds ratios generated from multivariate model (Table 2)

• Analyses completed using SAS 9.3 and LinkPlus

Objective

Kathleen Stigi, MPHEpidemiologist Katie.Stigi@doh.wa.gov(206) 418-5586

This study was supported in part by an appointment to the Applied Epidemiology Fellowship Program administered by the Council of State and Territorial Epidemiologists (CSTE) and funded by the Centers for Disease Control and Prevention (CDC) Cooperative Agreement Number 5U38HM000414

Results

Rotavirus vaccine coverage estimates using IIS data

Dose 1 Dose 2 Dose 32 months 4 months 6 months

Max: 14 wks, 6 days Max: 8 mo, 0 days1 http://www.cdc.gov/vaccines/recs/schedules/

Rotavirus vaccine coverage among 2010 birth cohort by county, WA State

Limitations

Methods

Conclusions

2010 Birth Cohort (WA IIS)

N = 87,301

Rotavirus Dose

n=70,350 (80.6)

Full Coverage

n=52,468 (60.1)

Partial Coverage

n=17,882 (20.5)

No Rotavirus Dose

n=16,951 (19.4)

No RV5n=6,678 (7.6)

No Vaccinen=10,273 (11.8)

* P-value < 0.05 when compared to ‘full’ coverage group+ Continuous variable – mean expressed

Full Coverage Three doses RV5 by 8 months

Partial Coverage One or two dose(s) RV5

No RV5 No RV5 dose (but ≥ one other dose between 6 - 15 weeks)

No Vaccine No vaccine dose (any) between 6 - 15 weeks

= outcomes of interest= reference group

Table 1. Maternal risk factors expressed as proportions among coverage groups

N= 62,597 matched records from 2010 birth cohort

Predictor Category% Full

Coverage n=44,167

% Partial Coverage n=13,431

% No RV5

n=4,999

Age <20 4.8 7.3* 5.2

 20-29 47.4 55.7* 47.3

 30-39 43.9 33.9* 42.6

 40-54 4 3.1* 4.9*

Race AI/AN 1.6 3.4* 3.6*

  Asian 8.6 5.3* 3.8*

  Black 4.8 7.6* 3*

  Hisp/Latino 10.8 11.5* 5.1*

  Pac. Islander 3.1 3.9* 2.2*

  White 71.1 68.4* 82.4*

Primiparous 46.4 35.1* 36.9*

Previous live births+ 0.9 1.3* 1.2*

Education ≤ High school 30.5 50.9* 36.8

  Some college 29.7 31.6* 34.3*

  ≥ 4yr College 33.5 17.5* 29.3*

Married   68.4 57.8* 71.1*

Medicaid   36.3 49* 36.9

Table 2. Maternal risk factors among 'partial' and 'no RV5' coverage groups compared to 'full' coverage group

N= 62,597 matched records from 2010 birth cohort     Partial Coverage No RV5

Predictor CategoryAdjusted OR

(95% CI)Adjusted OR

(95% CI)

Age <20 2.1 (1.85, 2.45) 1.4 (1.17, 1.78)

 20-29 1.5 (1.36 1.72) 1.0 (0.82, 1.12)

 30-39 1.1 (0.96, 1.2) 0.9 (0.74, 0.99)

 40-54 Reference Reference

Race AI/AN 1.5 (1.29, 1.65) 1.7 (1.45, 2.04)

  Asian 0.9 (0.86, 1.02) 0.4 (0.37, 0.50)

  Black 1.3 (1.20, 1.41) 0.5 (0.43, 0.60)

  Hisp/Latino 0.8 (0.70, 0.81) 0.4 (0.31, 0.41)

  Pac Islander 1.2 (1.06, 1.31) 0.6 (0.49, 0.74)

  White Reference Reference

Primiparous 0.8 (0.74, 0.84) 0.9 (0.79, 0.94)

Previous live births* 1.2 (1.18, 1.24) 1.2 (1.14, 1.22)

Education ≤ High school 1.7 (1.63, 1.86) 1.1 (0.99, 1.19)

  Some college 1.6 (1.46, 1.65) 1.2 (1.11, 1.31)

  ≥ College Reference Reference

Married   0.9 (0.83, 0.92) 1.2 (1.12, 1.31)

Medicaid   1.1 (1.05, 1.16) 1.1 (1.00, 1.17)

Acknowledgements

Background

Univariate Comparisons

Multivariate Results

* Odds for partial coverage and no RV5 increased by 20% with each previous birth / older sibling