Table 3 Risk criteria of illness severity or bacterial infection

High risk

New infiltrate on chest imaging, or ≥ 2 of any of the below risk criteria

  SIRS/qSOFA/SEP-1:

   Abnormal white blood cell count (> 12,000/µL or < 4,000/µL, or with greater than 10% bands)

   Abnormal temperature (< 36 or > 38 Celsius)

   Elevated heart rate (> 90)

   Elevated respiratory rate (≥ 22)

   Altered mental status

   Hypotension (systolic blood pressure < 90 or mean arterial pressure < 65 mmHg)

  Baseline demographics:

   Age ≥ 65 years

   Charlson comorbidity score > 2(8)

  Other:

   Clinician estimate of likelihood of bacterial etiology > 50%

   Oxygen saturation < 90%

   Hospitalized

Low risk

 No new infiltrate on chest imaging, AND

 No risk criteria of illness severity or  bacterial infection (as above)

Medium risk

 All other patients