The Malta Independent 4 June 2020, Thursday

Are you a suspect case of Coronavirus? WHO definitions of local transmission, contact tracing

Rebekah Cilia Tuesday, 24 March 2020, 10:15 Last update: about 3 months ago

The World Health Organisation (WHO) strongly recommends active case finding and testing as well as contact tracing in all transmission scenarios, something which the Maltese authorities have told us they are also doing.

Currently, the WHO has defined what a suspect, probable, and confirmed case is, but notes that countries may need to adapt case definitions depending on their local epidemiological situation and other factors. 

A suspect case is a patient with acute respiratory illness (fever and at least one symptom of respiratory disease, like cough or shortness of breath), and a history of travel or residence in a location reporting community transmission of COVID-19 disease during the 14 days prior to symptom onset.

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A patient with any acute respiratory illness and having been in contact with a confirmed or probably COVID-19 in the last 14 days, prior to symptom onset, also classifies as a suspect case, according to the WHO. A patient with severe respiratory illness, requiring hospitalisation and the in the absence of an alternative diagnosis that full explains the clinical presentation is also a suspect case.

A probable case is one for whom testing for the COVID-19 is inconclusive, or for whom testing could not be performed for any reason. 

A confirmed case is a person with laboratory confirmation of COVID-19, irrespective of clinical signs and symptoms. In Malta, the Superintendent for Public Health, Charmaine Gauci has noted that the test for the Coronavirus is performed multiple times to ensure a positive result is confirmed.

How is contact defined?

WHO defines what a contact is: this is a person who has been face-to-face with a probable or confirmed case within one meter, for more than 15 minutes. Gauci, also noted this in a press conference saying that "if a person simply passes by another person who might be infected, this does not mean that the virus is transmitted."

It could also mean direct physical contact with a probable or confirmed case, as well as direct care for a patient with probable or confirmed COVID-19 disease, without using proper personal protective equipment. There could also be other situation as indicated by local risk assessments.

All the above scenarios are defined as a contact by a person  during the two days before and 14 Fays after the onset of symptoms of a probable or confirmed case. 

As of 23 March, Malta had 90 confirmed cases of COVID-19, as per the case definition classified by the WHO, and has now progressed to the transmission classification noted as local.

What does local transmission mean?

Gauci has noted that Malta has now progressed to local transmission, but what does this mean? The WHO gives a transmission classification for all the countries in the world that have COVID-19 cases. This identifies the sources of how the virus spreads.

When identifying the source, the disease can be contained and steps can be taken to prevent the virus from transmitting to a wider number of people.

Community transmission means infections within a population are not imported from another virus-hit area but are spread through the community. Local transmission indicates locations where the source of infection is within the reporting location. Imported cases only indicates locations where all cases have been acquired outside the location of reporting.

What is contact tracing?

Gauci has also mentioned the term 'contact tracing' several times during the briefings and this means that attempts are made to trace all the people who a confirmed case may have been in close contact with. 

This is an essential process and a contact is defined by the WHO, as explained. Based on a risk assessment, usually using a case definition, authorities will aim to make contact with all of these people and take whatever appropriate action - testing, self-isolation etc - is needed.



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