Immunization Branch
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The TRIS is a school-based study conducted by the Texas Department of Health.
The TRIS measures immunization coverage rates of kindergarteners retrospectively
at two years of age. For example, the majority of the immunization records
reviewed for the 1999 TRIS were for children born in 1992-1993. Children were
considered up-to-date on their immunizations if they had completed the 4-3-1
series (4 doses of diphtheria-tetanus-pertussis vaccine, 3 doses of polio
vaccine, 1 dose of measles-mumps-rubella vaccine) by the time they turned two
years of age in 1994-1995.
Results showed the statewide 4-3-1 immunization rate at 24 months
of age at 63.7%. The TRIS 4-3-1-3 immunization rate (4-3-1 plus 3 doses of
Haemophilus influenzae type b vaccine) for the same age group was
58.7%.
Thus, 1999 TRIS data reflect the immunization coverage levels of
the 1998-1999 kindergarten population when they were 24 months of age
(about three years prior to the survey date) rather
than the levels of the 1998-1999 24-month old population.
View the Texas Immunization Rates
by Public Health Region (1999 TRIS).
Epidemiology Department
Galveston County Health District,
December 1999
Vaccination coverage of Galveston County preschool children was
assessed through a retrospective survey of immunization records for students
enrolled in kindergarten during the fall of 1999. These children became 2 years
of age in 1995-96. Eight hundred and sixty one records in 29 schools were
reviewed.
Survey results indicate that 56.2% of the children were adequately
vaccinated with DTP4, Polio3, and MMR1 (4-3-1 series) by age 2.
| County/City |
Estimated percent of vaccination coverage
with the 4-3-1 series* among 24
month olds
according to the Retrospective Immunization Surveys
conducted
by local health authorities |
| Galveston County |
56.2 |
| * Completion of 4 doses of
diphtheria-tetanus-pertussis vaccine, 3 doses of polio vaccine, 1 dose of
measles-containing vaccine |
Compared to 1998 survey results, at age 2, there was a small
decrease in the proportion appropriately vaccinated (from 57.7 to 56.2%). There
was also a decline (4.2%) in vaccination coverage at age 5; 85.2% were
adequately vaccinated with DTP4, Polio3, and MMR1 compared to 89.4% for students
enrolled in kindergarten during the fall of 1998. At ages 3 months, 7 months,
and 1 year, there were statistically significant increases in vaccination
coverage.
Ninety-five percent confidence intervals were calculated for each
estimated vaccination coverage level mentioned above. The increases were
significantly different from the 1998 survey, but the decreases were not. Each
of the last six annual surveys has shown improvement in the proportions of
children adequately vaccinated by ages 2 and 5. The 1999 survey results reflect
improvement of about 15% for 2 year olds and 7.5% for 5 year olds compared to
1993.
Substantial declines were observed again from the proportion
adequately vaccinated at age 3 months (80.3%) to that at age 7 months (51.5%),
and from age 12 months (77.2%) to age 19 months (45.9%). This is evidence of the
need for an effective vaccination tracking system that can generate reminders to
parents and providers.
Since the percentages of children at various ages who received
specific single vaccine doses were somewhat higher than the percentages of
children who had received the complete recommended series of vaccines, it
appears that medical providers do not always provide all age-appropriate
vaccines simultaneously.
The results of this survey can be used to select target areas for
special vaccination efforts. The localities served by the nine schools in which
students had the lowest vaccination levels at age 2 are recommended as target
areas. These include Galveston (east,west and central), Dickinson, High Island,
and Bacliff.
For a copy of the comprehensive report on the Galveston County
retrospective survey, contact Chuck Chambers, Galveston County Public Health
District, at (409) 765-2514.