Case definition and European surveillance for human infection with novel coronavirus (SARS-CoV-2)

Case definition

For surveillance at the European level, ECDC and the WHO Regional Office for Europe request countries to report probable and confirmed cases of SARS-CoV-2 infections using the global case definition within 24 hours after identification. EU/EEA countries must notify probable and confirmed cases of SARS-CoV-2 through the Early Warning and Response System (EWRS).

ECDC and the WHO Regional Office for Europe are coordinating the rapid reporting of data as requested in the WHO case reporting form in collaboration with their surveillance networks in Member States.

Case reporting forms will be collected using The European Surveillance System - TESSy.  

The World Health Organization has published technical guidance on  surveillance and case definitions. The guidance includes a case definition for suspect, probable and confirmed cases, and an interim case reporting form. The case definition for suspect cases was based on the information available on the outbreak at that time. Following the confirmation of community transmission in Wuhan and reports of a wider disease spectrum, ECDC updated the criteria for laboratory testing of suspect cases. The ECDC definition of suspect cases includes patients with acute respiratory infection (ARI) regardless of severity, that in the 14 days prior the onset of illness, had a close contact with a confirmed SARS-CoV-2 visited a healthcare facility where SARS-CoV-2 cases were being treated, or travelled to areas with presumed ongoing community transmission.


Case definition for surveillance

Suspected case requiring diagnostic testing (not to be reported at European level)

Patients with acute respiratory infection (sudden onset of at least one of the following: cough, sore throat, shortness of breath) requiring hospitalisation or not


In the 14 days prior to onset of symptoms, met at least one of the following epidemiological criteria: 

•    Were in close contact  with a confirmed or probable case of SARS-CoV-2 infection; 

•    Had a history of travel to areas with presumed ongoing community transmission


•    Worked in or attended a health care facility where patients with SARS-CoV-2 infections were being treated. 


Close contact

Close contact of a probable or confirmed case is defined as:

  • a person living in the same household as a SARS-CoV-2; 
  • a person having had face-to-face contact or was in a closed environment with a SARS-CoV-2 case; 
  • a healthcare worker or other person providing direct care for a SARS-CoV-2 case, or laboratory workers handling SARS-CoV-2 specimens;
  • a contact in an aircraft sitting within two seats (in any direction) of the SARS-CoV-2 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). Click here to read the guidelines.

The epidemiological link may have occurred within a 14‐day period before or after the onset of illness in the case under consideration.


Probable case 

A suspected case for whom testing for SARS-CoV-2 is inconclusive (the result of the test reported by the laboratory) or for whom testing was positive on a pan-coronavirus assay. 


Confirmed case 

A person with laboratory confirmation of SARS-CoV-2 infection, irrespective of clinical signs and symptoms 


Criteria to initiate testing for SARS-CoV-2

Prompt case confirmation is necessary to ensure rapid and effective contact tracing, implementation of infection prevention and control measures according to national recommendations, and collection of relevant epidemiological and clinical information.

Any person fulfilling the criteria for a suspected case should be tested for SARS-CoV-2. The laboratory method is provided below. The laboratory test should be initiated immediately.


Types of specimens 

Rapid collection of the following specimens should be considered:

When possible, specimens from both lower and upper respiratory tracts should be collected:

 Lower respiratory tract:

  • bronchoalveolar lavage (BAL)
  • endotracheal aspirate (ETA)
  • expectorated sputum

Upper respiratory tract:

  • nasopharyngeal swab
  • oropharyngeal swab
  • nasopharyngeal aspirate or nasal wash

Additional specimens for later testing:

  • when serological testing becomes available: serum, acute and convalescent (possibly 2-4 weeks after acute phase) specimen,
  • other specimens to consider: blood, urine and faeces


Practical guide for appropriate sampling, can be found in the WHO guide for field operations: Collecting, preserving and shipping specimens for the diagnosis of avian influenza A(H5N1) virus infection.

Respiratory specimen collection from the upper and in particular lower respiratory tract, should be performed under heightened infection prevention and control measures (airborne precautions) according to WHO interim guidance on Infection prevention and control in healthcare settings when novel coronavirus (nCoV) infection is suspected.

Currently there is limited information about the best point in time for specimen collection. Similar to other viral respiratory infections, it is likely that respiratory specimens collected early after symptom’ onset would yield higher virus concentrations. According to WHO interim guidance for clinical management of SARI, when nCoV infection is suspected, for hospitalised patients the frequency of specimen should be at least every 2 to 4 days until there are two consecutive negative results at least 24 hours apart.


Testing methodology

The specific tests currently recommended by WHO for the diagnosis and confirmation of SARS-CoV-2 are described in a dedicated WHO webpage, where the laboratory diagnostic protocol for real-time RT-PCR developed by Charité, Berlin Germany can also be found . 

It is recommended that the specimens of the first five positive cases and first 10 negative cases meeting the SARS-CoV-2 case definition for testing should be shipped for confirmation to the national specialised laboratory for SARS-CoV-2 or in lack of national capacity to one of the specialised laboratories that offered international support (see list of laboratories below). After that time, the laboratories can test for SARS-CoV-2 independently but use the specialised laboratories to resolve confounding results.

A single positive test should be confirmed by a second RT-PCR assay targeting a different SARS-CoV-2 gene. A single negative SARS-CoV-2 test (especially if from upper respiratory tract specimen) or a positive test result for another respiratory pathogen result does not exclude SARS-CoV-2 infection. If there is a strong suspicion for SARS-CoV-2 infection, another specimen should be tested with the primary and secondary RT-PCR assays.

When possible, sequence information should be generated from positive specimens. ECDC encourages the timely sharing of sequence data. Publically available sequence database GISAID is accepting the upload of SARS-CoV-2 sequences.




Are European laboratories ready to detect COVID-19?

News story -

A first assessment looking at the preparedness of EU/EEA laboratories to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) demonstrates a fast implementation of molecular diagnostics by the European specialised laboratory networks. It also shows a good geographical coverage for testing.