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Table 2 Official definitions of healthcare-associated coronavirus disease 2019 (COVID-19) cases and outbreaks

From: Nosocomial transmission and outbreaks of coronavirus disease 2019: the need to protect both patients and healthcare workers


Definition of cases

Definition of outbreak



Probable healthcare-associated COVID-19: a single inpatient who develops COVID-19 more than 7 days after hospital admission

Two or more cases in a single setting are detected that have become symptomatic or detected on screening on or after day eight of hospital admission



Not reported

LTCFs: a single laboratory-confirmed case of COVID-19 in a staff member (or resident)



• Onset of compatible symptoms ≥ 7 days after admission

• Onset of compatible symptoms 3–6 after admission if epidemiologically linked to hospital exposure

• Onset of clinical features of COVID-19 on day 1 or 2 after admission are considered community acquired unless epidemiologically linked to hospital exposure during a recent hospital admission

• If onset of clinical features cannot be defined, a case by case assessment is required taking account of the date of sampling relative to the date of admission, the CT value of the test result and epidemiological evidence of a link to hospital exposure.

Not reported



• Patient with new onset of COVID-19 compatible signs and symptoms* at least 5 days after hospital admission and a positive PCR result and/or thorax CT scan suggestive of COVID-19

• For hospitals with universal admission screening: Patient with negative PCR on admission and new onset of COVID-19 compatible symptoms and/or a positive PCR result at least 5 days after hospital admission

Detection of ≥ 3 nosocomial COVID-19 cases with a possible epidemiological (temporal and local) link


United States

• NOT considered nursing home onset COVID-19:

• Residents who were known to have COVID-19 on admission to the facility and were placed into appropriate Transmission-Based Precautions to prevent transmission to others in the facility.

• Residents who were placed into Transmission-Based Precautions on admission and developed SARS-CoV-2 infection within 14 days after admission

Notification required in case of:

 Residents or HCP with suspected or confirmed COVID-19

 Residents with severe respiratory infection resulting in hospitalization or death

 ≥ 3 residents or HCP with new-onset respiratory symptoms within 72 h of each other

[90, 91]

European Centre for Disease Prevention and Control

• Community-associated COVID-19 (CA-COVID-19): Symptoms present on admission or with onset on day 1 or 2 after admission

• Symptom onset on days 3-7 and a strong suspicion of community transmission..

• Indeterminate association (IA-COVID-19): Symptom onset on day 3-7 after admission, with insufficient information on the source of infection to assign to another category.

• Probable healthcare-associated COVID-19 (HA-COVID-19): Symptoms onset on day 8-14 after admission

• Symptom onset on day 3-7 and a strong suspicion of healthcare transmission.

• Definite HA-COVID-19: Symptom onset on day ≥14 after admission

Not provided Accessed December 26, 2020