Association between handwashing and gargling education for children and prevention of respiratory tract infections: a longitudinal Japanese children population-based study

Purpose A longitudinal study was conducted to examine the effects of handwashing and gargling education for children on the prevention of respiratory tract infections (RTIs) in children in Japan. Methods The study included 38,554 children born in 2010 who were enrolled in a longitudinal study. Information on children’s hygiene education regarding handwashing and gargling was collected in a survey at the age of 3.5 years. Based on parents' reports of doctors’ diagnoses, airway infections and influenza events in the 12-month duration before the survey were evaluated for RTIs at the ages of 4.5 and 9 years. Poisson regression with robust variance was performed to examine the effects of hygiene education on RTIs prevention. The supplementary analysis was stratified by household income. Results Children were categorized into different groups: 38% in the handwashing and gargling group, 29% in the handwashing group, 0.1% in the gargling group, and 9.7% in the no-education group. Exclusions were made for non-respondent children (23%) and those in the gargling group. Hygiene education was associated with decreased influenza at the age of 4.5 years in the handwashing (adjusted RR [aRR] = 0.8; 95% CI, 0.8–0.9) and handwashing and gargling groups (aRR = 0.8; 95% CI, 0.8–0.9) compared with no education. However, no preventive effects on airway infections at the age of 4.5 and 9, influenza at the age of 9, or hospitalization between the ages of 3.5 and 9 years were detected. Handwashing and gargling could significantly prevent influenza in low-income households (aRR = 0.7; 95% CI, 0.6–0.8). Conclusions : Gargling education was widespread and mostly combined with handwashing education in Japan. Hygiene education significantly affected prevention of influenza infections at the age of 4.5 years, especially in low-income households. What is Known: • Previous intervention studies showed handwashing and gargling are effective in preventing respiratory tract infections. What is New: • We conducted a longitudinal study on handwashing and gargling education in Japanese children and found that handwashing and gargling were widely practiced together. • Handwashing and gargling education were related to a reduction in influenza, particularly in low-income households.