A school-based educational on-site vaccination intervention for adolescents in an urban area in Germany: Feasibility and psychometric properties of instruments in a pilot study

Abstract

Background: Vaccination rates for measles, mumps, and rubella (MMR) and diphtheria, tetanus, pertussis, and polio (Tdap-IPV) are not optimal in German adolescents. Education in combination with easy access vaccination may be a promising approach to improve vaccination rates. In a planned cluster randomized controlled trial (cRCT), we aim at improving MMR and Tdap-IPV rates together with knowledge and self-efficacy in a school setting, the present paper describes the pilot study of this trial.Methods: Within this pilot study, 863 students from 41 school classes from four schools were included. Optimization and feasibility of the access to schools, recruitment strategies, intervention, and assessment procedures are examined. The course and content of the educational unit was evaluated with a mixed-methods approach. A pre-post measurement design was applied for the vaccination rate in all schools. Additionally, at two schools improvement on vaccination-related knowledge and perceived self-efficacy were measured pre- (n=287) and post- (n=293) educational unit by questionnaire. The remaining two schools provided data only post intervention. Finally, we evaluated the psychometric properties (i.e., reliability, retest reliability, change rates) of the questionnaire, applying Cronbach’s alpha, factor analyses, Generalized Estimating Equations and Linear Mixed Models.Results: Findings of the pilot study indicated good feasibility. Of the total sample, 437 students (50.9%) brought their vaccination cards to school, 68 students were vaccinated with Tdap-IPV, 11 with MMR. Out of 6 knowledge questions, on average students had M=2.84 (CI 2.69/3.10) correct answers before and M=4.45 (CI 4.26/4.64) after class. Ranging from 1 to 4, self-efficacy scale shown a change of 0.3 points (p <.001) and Cronbach’s alpha was .67 and .76 for pre- and post-educational unit respectively and a one-factor solution was found. Content analysis of the five semi-structured group interviews (n=12, 58.3% female) showed that the length of the intervention was felt by all students to be appropriate. The teaching methods including interactive and social media components were perceived as very good.Conclusion: A school-based educational and on-site vaccination intervention appears to be feasible in terms of procedures and the adequacy of the instruments for the adolescent target group.