The changing epidemiology of chickenpox in Alberta

Vaccine. 2005 Nov 16;23(46-47):5398-403. doi: 10.1016/j.vaccine.2005.05.008. Epub 2005 Jun 8.

Abstract

Background: Varicella vaccine was licensed in Canada in 1998. The province of Alberta introduced a universal publicly funded varicella vaccination program in 2001.

Purpose: To describe the epidemiology of non-fatal cases of chickenpox for which publicly funded health services were utilized for the period 1986-2002.

Methods: We used the records of Alberta's universal, publicly funded health care insurance system to identify cases of chickenpox for the period 1986-2002. The earliest dated utilization of a health service for which there was an ICD9-CM code of 052.xx or an IC10-CA code of B01.xx was used as the date of illness onset. Denominators for rates were estimated using mid-year population estimates from the Alberta Health Care Insurance Registry. Age-specific rates were estimated for each year.

Results: The crude incidence of chickenpox significantly declined over the period 1994-2002, most steeply after the year 2000. The incidence of chickenpox varied by age group and year and there was evidence of age-group-year interaction. Among those aged 5-19 years, chickenpox incidence began to decline prior to vaccine licensure in Canada. Among those aged less than one year and those aged 1-4 years, the incidence increased until 1999 when a decline began. Over the period 0.8% of cases were hospitalized.

Conclusion: Chickenpox rates began to decline prior to the introduction of the publicly funded vaccination program; however the declines in rates among the youngest age-groups are consistent with a vaccination program effect.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Aged
  • Alberta / epidemiology
  • Chickenpox / epidemiology*
  • Chickenpox / prevention & control
  • Chickenpox Vaccine
  • Child
  • Child, Preschool
  • Data Interpretation, Statistical
  • Databases, Factual
  • Delivery of Health Care / economics
  • Female
  • Hospitalization
  • Humans
  • Infant
  • Male
  • Mass Vaccination / legislation & jurisprudence
  • Mass Vaccination / trends
  • Middle Aged
  • National Health Programs
  • Seasons
  • Sex Factors

Substances

  • Chickenpox Vaccine