This is a feasibility double-blind randomised controlled trial in 32 participants. It evaluates the feasibility of a full trial which will examine the efficacy of weekly supplementation of cholecalciferol (vitamin D3) relative to placebo on the subsequent frequency and severity of objectively-verified symptomatic acute respiratory tract infection, overall and as a proportion of detected colonisations of the upper respiratory tract by 9 of the most common aetiologic viral pathogens.
The hypotheses of the full study are: Primary The group treated with vitamin D3 will have a significantly lower frequency of symptomatic respiratory tract infections than controls. Secondary 1. Among persons with detected viral colonisations of the nasopharynx, treated persons will have a lower frequency of symptomatic respiratory tract infection resultant than controls. 2. Treated group will have significantly less severe symptomatic RTIs than controls. 3. Treated group will have significantly shorter symptomatic RTI durations than controls. For the pilot, a cohort of 32 healthy young adults satisfying inclusion criteria will be randomised to cholecalciferol supplement or identical placebo and evaluated daily for the occurrence of RTI symptoms and evaluated weekly for the presence of respiratory colonisation by relevant pathogens using nasopharyngeal swab and polymerase chain reaction using selected pathogen-specific primers. This pilot will demonstrate the logistic feasibility of the proposed study design and provide preliminary data which will inform a larger study to be undertaken next year.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
TRIPLE
Enrollment
32
20,000 IU cholecalciferol capsule, given once weekly for 16 weeks.
Microcellulose capsule identical in appearance to treatment
Menzies Research Institute Tasmania
Hobart, Tasmania, Australia
Frequency of validated respiratory tract infections during study period
Frequency of validated respiratory tract infections during study period. Acute respiratory tract infections defined by respiratory symptoms reported by daily online survey lasting over a day and verified at exam by study nurse.
Time frame: 17 weeks
Proportion of colonisations leading to symptomatic respiratory tract infections
Proportion of colonisations with respiratory pathogens that go on to symptomatic verified respiratory tract infections. Colonisation detected by nasal swab sampled quantitiative RT-PCR.
Time frame: 17 weeks
Severity of respiratory tract infections during study
Severity (objective and subjective) of respiratory tract infections during the study. Subjective severity of symptoms reported by Likert scale (0-5) for each symptom. Objective severity by number and duration of symptoms.
Time frame: 17 weeks
Mean duration of respiratory tract infections during study
Mean duration of respiratory tract infections during study. Duration defined as number of days from participant-reported symptom onset to sympton resolution, as reported in daily online questionnaire.
Time frame: 17 weeks
Frequency of non-respiratory tract infections during study
Frequency of non-respiratory tract infections during study. Non-respiratory tract infections defined by non-respiratory symptoms reported by daily online survey lasting over a day and verified at exam by study nurse.
Time frame: 17 weeks
Concentration of serum 25-hydroxyvitamin D by the end of the study
Concentration of serum 25-hydroxyvitamin D by the end of the study
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Time frame: 17 weeks