Determining the clinical and cost-effectiveness of nasal sprays and a physical activity and stress management intervention to reduce respiratory tract infections in primary care: A protocol for the ‘Immune Defence’ randomised controlled trial.

Publication date: Jul 14, 2023

Most adults in the UK experience at least one viral respiratory tract infection (RTI) per year. Individuals with comorbidities and those with recurrent RTIs are at higher risk of infections. This can lead to more severe illness, worse quality of life and more days off work. There is promising evidence that using common nasal sprays or improving immune function through increasing physical activity and managing stress, may reduce the incidence and severity of RTIs. Immune Defence is an open, parallel group, randomised controlled trial. Up to 15000 adults from UK general practices, with a comorbidity or risk factor for infection and/or recurrent infections (3 or more infections per year) will be randomly allocated to i) a gel-based nasal spray designed to inhibit viral respiratory infections; ii) a saline nasal spray, iii) a digital intervention promoting physical activity and stress management, or iv) usual care with brief advice for managing infections, for 12 months. Participants will complete monthly questionnaires online. The primary outcome is the total number of days of illness due to RTIs over 6 months. Key secondary outcomes include: days with symptoms moderately bad or worse; days where work/normal activities were impaired; incidence of RTI; incidence of COVID-19; health service contacts; antibiotic usage; beliefs about antibiotics; intention to consult; number of days of illness in total due to respiratory tract infections over 12 months. Economic evaluation from an NHS perspective will compare the interventions, expressed as incremental cost effectiveness ratios. A nested mixed methods process evaluation will examine uptake and engagement with the interventions and trial procedures. Recruitment commenced in December 2020 and the last participant is expected to complete the trial in April 2024. Common nasal sprays and digital interventions to promote physical activity and stress management are low cost, accessible interventions applicable to primary care. If effective, they have the potential to reduce the individual and societal impact of RTIs. Prospectively registered with ISRCTN registry (17936080) on 30/10/2020. This RCT is sponsored by University of Southampton. The sponsors had no role in the study design, decision to publish, or preparation of the manuscript.

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Concepts Keywords
Antibiotic Activity
April Cost
Economic Days
Viral Infections


Type Source Name
disease VO effectiveness
disease IDO intervention
disease MESH respiratory tract infections
disease VO protocol
disease MESH infections
disease IDO quality
disease MESH comorbidity
disease IDO infection
disease MESH recurrent infections
disease VO monthly
disease MESH COVID-19
disease IDO process
disease VO effective
disease VO study design
disease VO population
disease IDO history
pathway REACTOME Reproduction
disease IDO antibiotic resistance
pathway KEGG Viral replication
disease IDO symptom
disease MESH chronic illnesses
disease MESH viral shedding
disease VO viable
disease MESH heart disease
disease MESH asthma
pathway KEGG Asthma
disease MESH lung disease
disease MESH stroke
disease MESH obesity
disease MESH dementia
disease MESH pituitary adenoma
disease VO report
drug DRUGBANK Esomeprazole
disease VO device
disease IDO immunosuppression
drug DRUGBANK Trestolone
disease VO Thing
disease MESH emotional distress
disease VO time
disease MESH allergy
disease IDO algorithm
drug DRUGBANK Etoperidone
drug DRUGBANK Ilex paraguariensis leaf
drug DRUGBANK Ademetionine
drug DRUGBANK Cysteamine
disease VO adverse event
disease MESH emergency
disease VO Viruses
drug DRUGBANK Coenzyme M
disease MESH common cold
disease VO nose
disease MESH Psychological stress
disease IDO susceptibility
disease MESH irritable bowel syndrome
disease IDO country
disease MESH anxiety disorders

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