Background
Vaccination is one of the most successful and effective tools for preventing infectious
diseases. However, despite the well-established benefits of vaccinations many children in
different regions of the world remain unvaccinated. Most of them live in developing
countries. Each year about 3 million people die from infectious diseases that could be
prevented through vaccinations. Many studies have investigated factors associated with the
vaccination status of children in both developing and developed countries. Different
patterns of association have been observed; in developing countries, socio-economic
factors, usually associated with health care access, play a more important role in
determining the vaccination status of a child. For example, in developing countries
children living in rural areas, of large families, with mothers who have a lower level of
education and a poor access to health care facilities were found to have a lower level of
vaccination. In developed countries children whose parents have negative beliefs towards
vaccinations are usually more often inadequately immunized. Not much is known about
factors associated with the vaccination status of children in the former Soviet countries.
These countries had, in general, a better socio-economic status than developing countries
and also well-organized health care system, including vaccination programmes. After the
collapse of the Soviet Union, these countries have experienced a deep financial and
political crisis, which has had a detrimental impact on the health status of the population.
These countries are in transition from one political system to another and were classified as
transitional countries by the World Bank. The World Health Organization also classified
the health care systems in these countries as health care systems in transition. Therefore,
the current situation in these countries is very specific. The question arises which health
status determinants play an important role in a time of transition, as different determinants
require different vaccination policies to adequately react to societal changes.
Objectives
The aim of this dissertation was to describe a vaccination process in a transitional country,
using the example of Kyrgyzstan. Among the specific aims of this dissertation was an
analysis of factors associated with children’s vaccination status. The study also aimed to
assess parental attitudes towards childhood vaccinations and to analyze factors associated
with them. An important aim of this study was an assessment of up-to-date and age-
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appropriate vaccination. Based on the results of the dissertation recommendations should
be given to vaccination policy makers.
Methods
Three sources of data were used in this work to answer different aims of the study. For the
assessment of up-to-date vaccination, which is defined as the proportion of vaccinated
children at a specific age, all three data sets were used, namely, the Demographic and
Health Survey (DHS) (1997), the Multiple Indicator Cluster Survey (MICS) (2005) and
data from an own cross-sectional study, which was conducted in the capital of Kyrgyzstan,
Bishkek, in September 2006. Age-appropriate vaccination, which should be administered
according to the immunization schedule in Kyrgyzstan, was assessed by using available
data from the DHS. For the analysis of risk factors associated with the vaccination status of
children, data from the MICS and the cross-sectional study in Bishkek was used.
The cross-sectional study among parents of first-year school children was conducted using
a self-administered questionnaire in 8 primary schools. Prior to the development of the
questionnaire, literature search was done in PubMed to identify relevant studies conducted
in both developing and developed countries. Information gained from the literature search
was used for the development of the questionnaire. Among a wide set of sociodemographic
variables, information on childhood vaccinations, parental attitudes towards
vaccinations, knowledge about vaccination, access to health care facilities, and health
status of children and parents were asked in the questionnaire. The questionnaire was
pretested in one school and minor modifications were introduced. Currently vaccines
against nine infectious diseases are administered in Kyrgyzstan. Questionnaires were
distributed to children at school with the request to have them completed at home by their
parents. Two days later the questionnaires were collected. A total of 934 questionnaires
were returned, which corresponded to the response rate of 89%. The study was conducted
in agreement with head masters of each school. The responses were anonymous.
Results
Up-to-date vaccination coverage
The up-to-date vaccination coverage based on all three data sources was at relatively high
levels but lower than reported by the local Ministry of Health. According to the DHS data,
up-to-date vaccination coverage among children of 12 to 35 months of age ranged between
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90% (measles vaccine) and 99% (first dose of polio vaccine). Up-to-date coverage
declined with an increasing number of doses (e.g. 98% for the first dose of DTP-vaccine,
95% for the second dose and 92% for the third dose). Up-to-date coverage for polio
vaccine declined to 90% for the third dose. The coverage for vaccine against tuberculosis
was 97%.
According to the MICS data, up-to-date coverage among children of 12 to 59 months of
age was highest for vaccine against tuberculosis (99%) and lowest for vaccine against
measles (95%). At least one dose of DTP- and polio vaccines received 99% and 97% of
children, respectively. However, a lower proportion of children was completely immunized
with all three doses (52% with DTP-vaccine and 60% with polio vaccine). About 24% and
15% of children received only one dose of DTP- and polio vaccines.
According to the study conducted in the capital Bishkek, 96% of first-year pupils (6-7
years of age) were vaccinated against tuberculosis and 89% against measles. At least one
dose of hepatitis B, DTP- and polio vaccines was administered to 81%, 94% and 96% of
children, respectively. However, only 83% of those children were vaccinated completely
with all three doses of DTP- and polio vaccines and 77% with all three doses of hepatitis B
vaccine.
Age-appropriate vaccination
The age-appropriate vaccination was much lower compared to up-to-date vaccination. A
substantial proportion of children was vaccinated with a considerable delay. About 85%
(95% CI: 82.6-87.8) of children were vaccinated with a first dose of DTP-vaccine without
any delay, 74% (70.1-79.2) with a second dose and 62.9% (59.3-66.6) with a third dose.
Although polio vaccine should be administered at the same schedule as DTP-vaccine, there
were some differences in age-appropriate vaccination. About 85% of children were
vaccinated with a first dose of polio vaccine, but only about 65% and 59% with second and
third doses, respectively. Only 75% of children received vaccine against measles without
any delay.
Parental attitudes towards vaccination
The perceived importance of childhood vaccinations among parents was at very high level;
about 96% of parents believed that vaccinations were important (about 40% very
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important). The overwhelming majority of parents had positive attitudes towards
vaccination. However, a small proportion of parents expressed some concerns regarding
vaccine safety. Moreover, about 15% of parents were opposed to mandatory vaccinations
and about 5% had strong anti-mandatory attitudes. Lower education of both parents was
associated with higher vaccine safety concerns and higher anti-mandatory attitudes.
Parents whose children had allergies, were also more likely to have higher vaccine safety
concerns and higher anti-mandatory attitudes. Internal migration was also associated with
anti-mandatory attitudes; parents, who migrated to the capital from other urban regions,
were more likely to have anti-mandatory attitudes. About 11% of parents would refuse
childhood vaccinations if they had another child in the future.
Factors associated with incomplete or missing vaccination
Multilevel logistic regression analyses of the MICS data showed that the only variable
significantly associated with the incomplete vaccination status of children was the wealth
index. The risk of not being completely vaccinated with DTP and polio vaccine was higher
among children from poorer families compared to those from richest families.
Results of the study conducted in the capital Bishkek showed that children who were not
born in the capital, with parents with no sources of vaccinations and with a poor access to
health care were more likely not to be vaccinated with the measles vaccine. The same
pattern of association was observed for vaccine against hepatitis B. Furthermore, children
whose parents had concerns about vaccine safety were also more likely not to be
vaccinated against hepatitis B.
Conclusions
Up-to-date vaccination coverage was at high levels according to all data sources and was
higher compared to other developing and even developed countries. Considerable
proportion of children was vaccinated with delay. Factors associated with no vaccination
were a mixture of patterns observed both in developing and developed countries. Some
parents had concerns about vaccine safety and a small proportion of parents had antimandatory
attitudes. Policy makers should take these findings into consideration in order
to adequately plan vaccination programmes.