Table 2

Summary of the national COVID-19 symptom checkers’ triage criteria

Triage criteria	Risk-based symptom checker	Severity-based symptom checker
Triage criteria	Singapore	CDC	NHS 111
Duration of symptoms	Duration of symptoms affects triage outcomes. Patients with symptoms over 4 days are always triaged in to further care.	Duration of symptoms does not alter triage outcomes. No length of illness leads to triage in to further healthcare contact.	Duration of symptoms does not alter triage outcomes. No length of illness leads to triage in to further healthcare contact.
Age	Age affects triage outcomes. Cases over the age of 65 years are always triaged on for further healthcare contact. During times of low SARS-CoV-2 healthcare burden, age is removed as a restriction to further clinical assessment.	Age affects triage outcomes Cases over the age of 65 years are now triaged on to further healthcare contact.	Age has no bearing on triage advice for the NHS symptom checkers in England, Scotland and Northern Ireland. NHS Wales triages all cases over the age of 70 years to contact ‘111’.
Comorbidity	Comorbidity affects triage outcomes. Cases with any comorbidity are triaged on to further care.	Comorbidity affects triage outcomes. Cases with moderately severe comorbidities are triaged on for further healthcare contact.	Comorbidity affects triage outcomes. The type of comorbidity triggering triage on to further healthcare contact differs across the four nations.*
Shortness of breath	Any degree of shortness of breath is triaged straight to the emergency department.	Patients with severe breathlessness are triaged to the emergency department. Patients with mild to moderate shortness of breath are advised to stay home with no clinical follow-up.	Patients with severe breathlessness are triaged to the emergency department. NHS England triage cases in to further care if self-rated breathlessness is mild to moderate and is the primary symptom, but not if a secondary symptom. Scotland, Northern Ireland and Wales triage all patients self-reporting breathlessness to urgent ‘111’/General Practioner. If severe, the patient is advised to call ‘999’.

*NHS Scotland only triages cases with comorbidities that are on the shielding category list for further care. NHS Northern Ireland only triages cases with immunosuppression or conditions that have become more difficult to control since symptoms began. NHS Wales relies on shielding categories and also includes diabetes and pregnancy with heart conditions. NHS England use shielding categories and also consider immunosuppression, diabetes, heart disease, respiratory disease, kidney failure, liver disease or neurological disease.