Laboratory testing for probable case is defined as:
a) people with acute respiratory tract infection symptoms with no indication of any other cause and having been in close contact with a confirmed or probable COVID-19 case in the last 14 days prior to the onset of symptoms;
b) people with acute respiratory tract infection symptoms with no indication of any other cause and have visited countries with confirmed cases 14 days prior to the onset of symptoms.
c) severe acute respiratory tract infection with no indication of any other cause required hospital admission.
Close contact is defined as a) living in the same household; b) caring for a sick person, including medical personnel and laboratory personnel; c) being in direct contact with body fluids from a sick person or in direct physical contact with a sick person; d) being in close face-to-face contact with a sick person for at least 15 minutes within 2 meters; e) being in in the same room with sick person at least 15 minutes within 2 meters; and f) sitting close to a sick person during a flight.
Contact tracing is implemented by the RHIs. Someone who had close contact with a person with confirmed COVID-19 is registered and has to be tested.
The surveillance of COVID-19 is regulated by orders of the Minister of Health and is based on the respiratory disease surveillance system, according to the ordinance on notification, registration and reporting of communicable diseases. The RHIs have to report immediately every confirmed case to the MoH. The RHIs deliver summarised information to the National Centre of Public Health and Analysis on a daily basis, and the latter synthesises received data and prepares daily and weekly epidemiological bulletins for the MoH.
A mobile application (ViruSafe) with voluntary self-reporting symptoms, some personal data (such as age and chronic diseases) and the location has been activated. This app is a component of a national informational COVID system, which will facilitate the integration and coordination between all involved authorities and health care establishments. Existed data about confirmed cases and individuals under quarantine have been already integrated into the system. The system describes diffusion in space and time of the spread across the country and will serve for modelling and forecasting the trends.
A panel testing surveillance has been initiated by the National Operational Headquarters and the MoH based on a sample of 1,000 police officers. The results will be used for the development of a mass screening strategy. Such mass testing has been conducted in the town Bansko, where several COVID-19 cases prompted the government to impose a full 14-days shutdown of the resort.
Reported COVID-19 deaths include all confirmed cases based on testing, irrespective of the setting. In mid-April, the National Operational Headquarters announced that all death cases during the epidemic are to be analysed in comparison to the previous year in regard to revealing possible "hidden" COVID-19 deaths. The National Statistical Institute has started publishing 2020 weekly death rates compared to the previous year on its website.
On June 3, the Ministry of Health adopted some changes to the definition of COVID-19 case. Several criteria have been determined, divided into four groups:
a) clinical criteria: people with at least one of the following symptoms – cough; fever; dyspnoea; sudden emergence of anosmia, ageusia or dysgeusia. As additional and less typical symptoms are classified headache, chills, muscle pain, fatigue, vomiting and/or diarrhoea;
b) image diagnostic: radiologic characteristics of lesions typically for COVID-19 infection;
c) laboratory diagnostic: laboratory detection of SARS-COV-2 nucleic acid;
d) epidemiologic criteria: people with at least one of the following epidemiological connections - close contact with a confirmed COVID-19 case in the last 14 days prior to the onset of symptoms OR resident or employee of a social services facility with confirmed COVID-19 case in the last 14 days prior to the onset of symptoms.
A possible case is defined as every person meeting clinical criteria. A probable case is a person with symptoms and epidemiological connection OR person with radiologic characteristics. A confirmed case is a person with a positive PCR test.
Everyone who had close contact with a person with confirmed COVID-19 48 hours before and 14 days after the onset of symptoms or laboratory confirmation (in case of an asymptomatic patient) is registered by the RHI and has to be tested.
Sources and links:
Ministry of Health; https://www.mh.government.bg/bg/
National Statistical Institute. COVID-19 Section; https://www.nsi.bg/bg/node/18120/