Abstract |
Introduction: Adolescents, this unique age group between childhood and adulthood, are considered a target group of prominent importance for the application of immunization practices, that aim to prevent future infective diseases associated with adult life, to booster already acquired but progressively waning immunity and to catch- up vaccination doses due since childhood. In Greece, the National Immunization Schedule recommends 3 vaccines at the age of 11-12 and till the age of 18 years old: tetanus and reduced diphtheria and acellular pertussis vaccine (Tdap), quadrivalent meningococcal conjugate vaccine (MenACWY) and, only for girls, human papillomavirus vaccine (HPV). However, low immunization rates are reported both globally and nationally for the above- mentioned vaccines within the adolescent population. The present study aims to investigate the immunization status of High School students in the Municipality of Festos, a non- urban Municipality in Heraklion Prefecture, Crete
Methods: High school students’ Child Health Booklets were collected during a period between November 2018 and April 2019 from the five High Schools in the Municipality of Festos. For every participant the following information was transcribed: sex, date of birth, school of origin, number of administered doses of each one vaccine of childhood and adolescence as well as the dates of administration for Tdap, MenACWY and first dose of HPV vaccine. Rates of vaccination coverage were calculated for the whole of vaccines and for every vaccine separately, and any statistically significant associations with sex, age and school of attendance were investigated. Especially for adolescent vaccination rates, a possible association with childhood immunization status was also investigated. Statistical methods used were chi- square and Fischer exact tests, and the level of statistical significance was defined at 0.05.
Results: 246 High School students in the Municipality of Festos participated in the study and among them 35.8% (95% CI 29.8%-41.8%) were found fully vaccinated for all the vaccines included in the National Immunization Schedule. Childhood vaccinations had been fully administered to 63.8% (95% CI 57.8-69.8%) of the students, while those of adolescence to 51.6% (95% CI 45.4%-57.8%), without any statistically significant correlation between them. Among childhood vaccines, higher vaccination rates were observed for hepatitis B vaccine (99.2%, 95% CI 98.1%-100%) and poliomyelitis vaccine (98.8%, 95% CI 97.4%-100%), and the lowest for the conjugate pneumococcal vaccine (75.4%, 95% CI 69.9%-80.9%). The vaccines destinated for the age of adolescence presented lower vaccination rates, as follows: Tdap 65% (95% CI 59%- 71%), MenACWY 82.5% (95% CI 77.8%-87.2%) and HPV 68.2% (95% CI 60.8%-75.6%).
Discussion/ Conclusions: In spite of its limitations, that mainly concern the small sample size and its heterogeneity, the present study suggests still suboptimal, although higher in comparison to previous similar studies, adolescent vaccination rates in a non- urban region in Crete. Among the possible contributing factors, only the infrequent co-administration of vaccines was possible to identify with this study’s design. However, it is suggested that the impact of socio-economic factors, along with parents’ and adolescents’ limited knowledge concerning immunizations may also contribute to the low vaccination rates observed. Further research on the specific reasons for low immunization rates of adolescents in this region is needed, in order to develop appropriate Public Health strategies that could help improve adolescent vaccination.
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