Please select the eligibility criteria that correspond to the clinical trial below.
Title: McFlu2 COLD3 Prevention: A Randomized, Placebo-controlled, Double Blind Trial of Vitamin D and Health Advice for the Prevention of Upper Respiratory Tract Infections in McMaster University Students
Brief Summary: The specific objectives of this investigation are to assess the effectiveness of daily gargling and vitamin D supplementation as preventative measures against incident upper respiratory tract infection (URTI) in students attending McMaster University. Investigators hypothesize that

1. Vitamin D3 supplementation will decrease the incidence of symptomatic upper respiratory tract infections in university students
2. Gargling will decrease the incidence of symptomatic upper respiratory tract infections in university students.


Options:
A: Inclusion Criteria:

* Current or part-time student at McMaster University
* 17 year of age or older
* Currently living:

  i. In residence or, ii. Off-campus with at least one student housemate
* Willing and able to sign an informed consent

Exclusion Criteria:

* Students who do not meet the inclusion criteria
* Currently living at home with parents
* History or diagnosis of hypercalcemia
* Diagnosis of parathyroid disorder (hyper or hypo)
* Diagnosis of chronic kidney disease
* Use of anticonvulsants
* Malabsorption syndromes
* Diagnosis of sarcoidosis
* Currently pregnant or planning a pregnancy
* Inability to swallow capsules
B: Inclusion Criteria:

* Nursing homes which contain a medical coordinator and at least one nurse and/or nursing auxiliary.
* Nursing Homes located in France (North-West)
* All the residents present or entering the facility during the study period

Exclusion Criteria:

* Nursing homes where a prevention program has already been implemented
C: Inclusion Criteria:

* Health care workers who provide direct care to patients with suspected or confirmed COVID-19 in specialized COVID-19 units and in emergency departments, medical units, pediatric units, and long-term care facilities
* Health care workers are required to spend 60% or more of their time doing clinical work when enrolled.

Exclusion Criteria:

* Unable to pass or do not have a valid fit test within the past 24 months
* One or more high-risk comorbidities for COVID-19 (hypertension, cardiac disease, pulmonary disease, chronic kidney disease, diabetes, chronic liver disease, actively treated cancer, or immunosuppression due to illness or medications)
* Previous laboratory confirmed clinical diagnosis of COVID-19 at the time of
* Received 1 or more doses of a COVID-19 vaccine with greater than 50% efficacy for the circulating strain (for example, mRNA or vector-based COVID-19 vaccine against the original SARS-CoV-2 strain).
* working in intensive care units.
D: Inclusion Criteria:

* aged from 15 to 20 years
* obtained written informed consent from both the student and parent before participation
* possible to gargle during 90 days
* possible to fill in questionnaire

Exclusion Criteria:

* Possessing allergy to green tea
* Possessing history of influenza infection within 6 months before entering the study
* Possessing severe immune disease or whole body infection
* severe cardiac, respiratory, renal, or hepatic dysfunction
* diagnosed as inadequate to participate in the study by student doctor

Answer: A