Serbia uses the WHO COVID-19 case definition (https://covid19.rs/). A probable case is defined as a suspected case for which testing for COVID-19 virus is inconclusive or who is epidemiologically linked to a confirmed or probable case (a person with acute respiratory disease who had close contact with a confirmed or probable case of COVID-19 for up to 14 days before the onset of symptoms) or a person who worked in a healthcare facility in which confirmed patients were treated.
The physician, during the first contact with a possible or probable COVID-19 case, makes a list of the patient's close contacts after the onset of the first symptom of the disease. The data are sent for each patient to the epidemiologist of the territorially competent public health institute. The epidemiologist then contacts all persons from the list and informs them about the 14-day self-isolation measure that is being controlled by sanitary inspectors.
On 24 January 2020 an algorithm (SOP) was issued on the syndromic surveillance of potential COVID-19 patients, based on case definitions given in the algorithm. This algorithm has been revised several times, with the last revision on 18 March 2020 (https://covid19.rs/).