A Population-Based Cohort Study of Undervaccination in 8 Managed Care Organizations Across the United States

Abstract

OBJECTIVES To examine patterns and trends of undervaccination in children aged 2 to 24 months and to compare health care utilization rates between undervaccinated and age-appropriately vaccinated children. DESIGN Retrospective matched cohort study. SETTING Eight managed care organizations of the Vaccine Safety Datalink. PARTICIPANTS Children born between 2004 and 2008. MAIN EXPOSURE Immunization records were used to calculate the average number of days undervaccinated. Two matched cohorts were created: 1 with children who were undervaccinated for any reason and 1 with children who were undervaccinated because of parental choice. For both cohorts, undervaccinated children were matched to age-appropriately vaccinated children by birth date, managed care organization, and sex. MAIN OUTCOME MEASURES Rates of undervaccination, specific patterns of undervaccination, and health care utilization rates. RESULTS Of 323 247 children born between 2004 and 2008, 48.7% were undervaccinated for at least 1 day before age 24 months. The prevalence of undervaccination and specific patterns of undervaccination increased over time (P < .001). In a matched cohort analysis, undervaccinated children had lower outpatient visit rates compared with children who were age-appropriately vaccinated (incidence rate ratio [IRR], 0.89; 95% CI, 0.89- 0.90). In contrast, undervaccinated children had increased inpatient admission rates compared with age-appropriately vaccinated children (IRR, 1.21; 95% CI, 1.18-1.23). In a second matched cohort analysis, children who were undervaccinated because of parental choice had lower rates of outpatient visits (IRR, 0.94; 95% CI, 0.93-0.95) and emergency department encounters (IRR, 0.91; 95% CI, 0.88-0.94) than age-appropriately vaccinated children. CONCLUSIONS Undervaccination appears to be an increasing trend. Undervaccinated children appear to have different health care utilization patterns compared with age-appropriately vaccinated children.

Undervaccination with diphtheria, tetanus, and pertussis vaccine: National trends and association with pertussis risk in young children

“…Contrary to the rising trend in the US, 13,14 this analysis also suggested that undervaccination in Taiwan decreased over time. The decreasing prevalence and magnitude of undervaccination against pertussis highlighted public health successes in improving access to healthcare, vaccine delivery, and systems to identify and catch up children behind on immunizations over the past decade.…”

“…Second, prior studies estimate that overall 10%-25% of children were undervaccinated because of vaccine-hesitant parents. 13,16,17 Our study, however, was unable to provide reasons for undervaccination as this information was not captured in the NIIS or assessed through reviews of medical records. Third, pertussis is highly underreported.…”

“…Days undervaccinated for specific doses were calculated based on a modified metric 7,12,13 that measures the difference between when the vaccine dose was administered and when the vaccine dose should have been administered (Table S1). The magnitude of undervaccination accumulated until the child was vaccinated or at age 36 months.…”

“…13 Time trends were analyzed with linear regression and CochranArmitage trend tests. Trends in undervaccination of dose 1, 2, or 3 were compared with dose 4 across the birth cohorts.…”

Cognitive factors of differences in vaccination patterns: the perceived risks of action and inaction

“…Иммунизация является одним из наиболее значимых достижений обществен-ного здравоохранения за последнее столетие [1]. Однако в последнее время серьез-ную обеспокоенность среди научного сообщества вызывает снижение уровня вак-цинации в мире, обусловленное не недостатком ресурсов, а осознанным отказом от вакцинации [см., например : 2, 3].…”