Process evaluation of the flucare cluster randomised controlled trial: assessing the implementation of a behaviour change intervention to increase influenza vaccination uptake among care home staff in England.

Background: Influenza (flu) vaccination rates of Care home staff (CHS) in England are consistently lower (≈ 15% in 2023) than World Health Organisation recommendations (≥ 75%). The FluCare trial examined the effectiveness of a multi-component intervention (including on-site flu vaccination clinics, information materials including video, £850 incentive and monthly monitoring with feedback) designed to address known barriers to flu vaccine uptake amongst CHS. This paper reports an embedded process evaluation designed to understand implementation of the FluCare intervention and provide explanations for observed effects in the trial.

Methods: The FluCare cluster randomised controlled trial was conducted between November 2022 and March 2023. A mixed methods process evaluation was conducted employing questionnaires, semi-structured interviews, video analytics (no. clicks and duration of view) and clinic logs (no. clinics delivered, days/time clinics were delivered, and no. staff vaccinated). CHS (including managers) and vaccination providers (pharmacists, nurses and general practitioners) were purposively and conveniently selected, respectively, for the interviews. Descriptive statistics were obtained for quantitative data, and qualitative data were analysed thematically.

Results: FluCare intervention implementation varied across Care homes (CHs), with clinics and videos not being implemented in 35% and 43% of the intervention CHs respectively. In addition, clinic days and times varied depending on provider (pharmacy or general practice) and CH. Partial intervention implementation was partly influenced by managers' engagement and sub-organisational cultures marked by negative narratives around vaccines. Contextual barriers included delivery of clinics late in the flu season. A greater indication of implementation fidelity was positively associated with change in staff attitudes and behaviours, with some getting vaccinated for the first time.

Conclusions: Variation in implementation of the FluCare intervention provides an explanation for detecting a difference where the intervention was fully implemented in the main trial. Manager and leader engagement is vital for both successful implementation and staff engagement. Avoidable contextual barriers, such as late timing of clinics, must be addressed to enhance flu vaccination uptake by CHS. More work is needed to understand the role of CH leaders in influencing intervention implementation, sub-organisational cultures and vaccination attitudes.

Trial Registration: ISRCTN22729870. Registered on 24 August 2022.