Viral respiratory tract infections are very common in children. They contribute to missed time in school, work disruption for caregivers and can also cause severe illness requiring hospitalization and rarely death. In the 2022-2023, influenza, RSV and SARS-CoV-2 viruses infected a large number of children which strained the pediatric healthcare system in many jurisdictions. Unfortunately, there continues to be limited data on duration of infectiousness and transmission risk of these viruses to inform public health decisions during times when there is significant circulation of these viruses.

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

Individuals with acute symptomatic influenza, RSV, SARS-CoV-2, mycoplasma pneumoniae, or bordetella pertussis infection identified through hospital testing (inpatient, outpatient, staff household members) or the school-based take-home saliva testing program.

Data elements will be made available by request with appropriate documentation and approvals.

Data will be made available once the study is complete and published.

upon request with appropriate approvals