Surveillance definitions for COVID-19

High-risk exposure/close contact

For the purpose of the EU case-definition, a close contact of a confirmed case is defined as:

  • A person living in the same household as a COVID-19 case;
  • A person having had direct physical contact with a COVID-19 case (e.g. shaking hands);
  • A person having unprotected direct contact with infectious secretions of a COVID-19 case (e.g. being coughed on, touching used paper tissues with a bare hand);
  • A person having had face-to-face contact with a COVID-19 case within 2 metres and > 15 minutes;
  • A person who was in a closed environment (e.g. classroom, meeting room, hospital waiting room, etc.) with a COVID-19 case for 15 minutes or more and at a distance of less than 2 metres;
  • A healthcare worker (HCW) or other person providing direct care for a COVID-19 case, or laboratory workers handling specimens from a COVID-19 case without recommended personal protective equipment (PPE) or with a possible breach of PPE;
  • A contact in an aircraft sitting within two seats (in any direction) of the COVID-19 case, travel companions or persons providing care, and crew members serving in the section of the aircraft where the index case was seated (if severity of symptoms or movement of the case indicate more extensive exposure, passengers seated in the entire section or all passengers on the aircraft may be considered close contacts).

Transmission status at national or sub-national level

The transmission status at NUTS2 level according to the WHO transmission classification should be reported to TESSy on weekly base using recordtype: NCOVCLASSIFICATION.

No cases: Countries/area/territories with no cases

Sporadic cases: Countries/area/territories with 1 or more cases, imported or locally detected

Clusters of cases: Countries/area/territories experiencing cases clustered in time, geographic location and/or common exposure

Community transmission: Countries/area/territories experiencing larger outbreaks of local transmission defined through an assessment of factors including, but not limited to:

  • Large numbers of cases not linked to transmission chains
  • High proportion of SARS-CoV-2 positive cases from sentinel lab surveillance
  • Multiple unrelated clusters in several areas of the country/territory/area

Deaths due to COVID-19

Mortality monitoring should be conducted according to the WHO definition:

A COVID-19 death is defined for surveillance purposes as a death resulting from a clinically compatible illness in a probable or confirmed COVID-19 case, unless there is a clear alternative cause of death that cannot be related to COVID disease (e.g., trauma). There should be no period of complete recovery between the illness and death.

A death due to COVID-19 may not be attributed to another disease (e.g. cancer) and should be counted independently of pre-existing conditions that are suspected of triggering a severe course of COVID-19.

 Number of deaths due to COVID-19 should be reported to TESSy on weekly base (case-based or aggregated data).

Source of infection: healthcare (nosocomial) vs community transmission

The source of a COVID-19 case can be community-associated (CA-COVID-19) or healthcare-associated (HA-COVID-19), based on the number of days until the onset of symptoms, or positive laboratory test, whichever is first, after admission to a healthcare facility (on day 1). Healthcare facilities include hospitals and long-term care facilities. This is informed by current knowledge regarding the distribution of incubation periods (Lauer SA et al. Ann Intern Med. 2020;172:577-582. doi:10.7326/M20-0504). If required, a case-by-case evaluation of the source should take into account COVID-19 prevalence in the institution/ward, contact with known cases in the community or the healthcare facility, and any other data that plausibly indicate the source of the infection.  The case source definitions are as follows:

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

Cases with symptom onset within 14 days of discharge from a healthcare facility (e.g. re-admission) may be considered as community-associated, probable or definite HA-COVID-19, or to have an indeterminate association. The designation of such cases should be made after a case-by-case evaluation.

The definition above does not apply to healthcare workers. The same categories may be used to classify the source of infection among healthcare workers, but should be based on a case-by-case assessment of the likelihood of exposure to COVID-19 cases in the healthcare setting or in the community. 

Suspected COVID-19 reinfection case

A suspected COVID-19 reinfection case is defined as:

Positive PCR or rapid antigen test (RAT) sample ≥60 days following:

  • Previous positive PCR
  • Previous positive RAT
  • Previous positive serology (anti-spike IgG Ab)
Page last updated 15 Mar 2021