BackgroundA prolonged COVID-19 pandemic could exacerbate the risk of infection and undesirable effects associated with infection control measures of older people with dementia (PWD), and the care burden of families. In this study, we examined the efficacy of care manager-led information provision and practical support for families of older PWD who need care, regarding appropriate infection prevention, prevention of deterioration of cognitive and physical functions, and preparedness in cases of infection spread or infection during the pandemic.MethodsFifty-three family members (aged ≥20 years) who were primary caregivers living with older PWD using public long-term care services were enrolled in an one-month randomized controlled trial. This duration was set based on behavior modification theory and with consideration of ethical issue that the most vulnerable people not benefiting from the intervention. The intervention group (IG) received care manager-led information provision and practical support, and the control group (CG) received usual care. Care burden (primary outcome) was measured using the Zarit Caregiver Burden Interview, and secondary outcomes were analyzed using Patient Health Questionnaire-9 (PHQ9), the Fear of COVID-19 Scale, and salivary α-amylase activity. Data were collected at baseline and after 1 month. Multiple regression analysis was conducted to examine the efficacy of the intervention. The participants evaluated the care managers’ support.ResultsThe participants were randomly divided into IG (n = 27) and CG (n = 26) groups. After the intervention, compared with the CG, there was a decrease in PHQ-9 (β = −.202, p = 0.044) and α-amylase activity in saliva (β = −.265, p = 0.050) in IG. IG also showed an increased fear of COVID-19 after the intervention (β = .261, p = 0.003). With the care managers’ support, 57.2% of the participants felt secure in their daily lives and 53.1% agreed that they were able to practice infection prevention suitable for older PWD.ConclusionsOur findings suggest that the care manager-led intervention may be useful for families of older PWD to enhance behavioral changes in preventing COVID-19 infection and improve their psychological outcomes in the COVID-19 era.Trial registrationThis study was registered on April 2, 2021 (No. UMIN000043820).