Inclusion Criteria:

Viral dynamics (primary outcome):

• The child must be less than 18 years of age
• Have a positive PCR sample for influenza, RSV or SARS-CoV-2,
• Have any one of the symptoms listed to meet testing eligibility: fever, cough, shortness of breath, decreased or loss of taste or smell, muscle aches/joint pains (unusual, long lasting, not related to injury), extreme tiredness (unusual fatigue not otherwise explained), sore throat, runny or stuffy/congested nose, headache (new, unusual, long-lasting), nausea/vomiting and/or diarrhea, and
• Be within 5 days of symptom onset

Household testing inclusion criteria (secondary outcome):

-Any individual in the same household (i.e. household contacts, defined as residing at the same address) as the individual testing positive by PCR for influenza, RSV, SARS-CoV-2, mycoplasma pneumoniae, or bordetella pertussis

Classroom testing inclusion criteria (secondary outcome):

-Any individual in the same classroom (i.e. classroom contacts) as the individual testing positive by PCR for influenza, RSV, SARS-CoV-2, mycoplasma pneumoniae, or bordetella pertussis (i.e. case identified through the THS program)

Exclusion Criteria:

Viral dynamics (primary outcome):

-Participants will be ineligible if they are more than 5 days from symptom onset