Title : Multicomponent school-based strategies to improve influenza vaccination uptake in low-resource China: Interim analysis of a five-arm cluster-randomized trial
Abstract:
Background: Influenza vaccination is an effective measure for preventing influenza and its complications, yet vaccine uptake among children remains low in many parts of China, particularly in low-resource settings. Evidence on how multilevel school-based intervention strategies can improve influenza vaccination uptake in such settings remains limited. We evaluated the interim effectiveness of a five-arm cluster-randomized controlled trial among primary school students in Tongren, Guizhou, China.
Methods: Classes were randomized to 1 of 5 groups: health education plus school-based vaccination for students and parents (HE+S/P-SBV), health education plus school-based vaccination for students (HE+S-SBV), health education only (HE only), student/parent school-based vaccination (S/P-SBV), or usual practice (control). The 4-week intervention was designed as a multilevel school-based implementation package involving students, caregivers, teachers, schools, local Centers for Disease Control and Prevention, and vaccination providers. Depending on group assignment, the intervention combined staged weekly activities, including a letter to parents, educational videos, illustrated materials, digital messaging and reminders, participatory learning through student poster drawing, and school-based vaccination opportunities. Baseline and follow-up questionnaires were administered before and after the intervention. For this interim analysis, the primary outcome was student influenza vaccination uptake during the prespecified observation window from November 15 to December 31, 2025, identified through linkage of class rosters, school-based vaccination records, and the immunization information system. Group differences were assessed using generalized estimating equations with class-level clustering, adjusting for school and pre-intervention influenza vaccination history.
Results: A total of 2,977 students were included. During the prespecified observation window, 167 students (5.61%; 95% CI, 4.84%–6.49%) received influenza vaccination, including 127 through the school-based program and 40 through non-school-based channels. Vaccination uptake ranged from 1.60% in the control group to 9.35% in the S/P-SBV group. In cluster-adjusted analyses, uptake was significantly higher than in the control group for HE+S/P-SBV (adjusted RR, 3.69; 95% CI, 1.39–9.84; P=0.009), HE+S-SBV (adjusted RR, 3.88; 95% CI, 1.44–10.48; P=0.008), and S/P-SBV (adjusted RR, 4.75; 95% CI, 1.84–12.27; P=0.001), whereas HE only did not differ significantly from control (adjusted RR, 2.31; 95% CI, 0.79–6.73; P=0.126). Students with documented pre-intervention influenza vaccination history were also more likely to be vaccinated during the intervention period (adjusted RR, 2.56; 95% CI, 1.80–3.64; P<0.001). Similar findings were observed among students without documented influenza vaccination during September 2021 to April 2025.
Conclusions: In this interim analysis, school-based intervention strategies that improved vaccination access were associated with higher influenza vaccination uptake than usual practice during the intervention period. These findings support multilevel school-based delivery approaches integrating health education, digital engagement, participatory learning, and vaccination convenience to improve vaccine uptake in low-resource settings.
