Any asymptomatic person who meets the definition of contact should be informed and active surveillance initiated. If during the 14 days after exposure the person develops respiratory symptoms; he/she must immediately self-isolate at home and urgently contact the person in charge. Contacts who develop respiratory symptoms during their follow-up; within 14 days of exposure; even if they do not meet the clinical case criteria; should be investigated to rule out infection by the new coronavirus; considering them a case under investigation. If the result is positive; and does not require hospitalization; isolation will be recommended; which may be at home or in the place established by the Public Health Authorities; 22/05/2020: All suspected cases of SARS-CoV-2 infection will undergo a PCR (or other molecular diagnostic technique) in the first 24 hours. If the PCR is negative and there is a high clinical suspicion of COVID-19; the PCR will be repeated with a new sample from the respiratory tract. If the PCR continues to be negative and several days have elapsed since the onset of symptoms; IgM detection may be considered using an ELISA-type serological test or other high-throughput immunoassay techniques; 08/06/2020: same as before; 19/06/2020: As soon as a suspected case is detected; activities to identify close contacts will begin. The period to be considered will be from 2 days before the onset of symptoms of the case until the moment in which the case is isolated. If the PCR of the suspected case is negative; the identification and control of the contacts will be suspended. In asymptomatic cases confirmed by PCR; contacts will be searched from 2 days before the date of diagnosis; 21/12/2020: Any person who is identified as a close contact must be informed and active or passive surveillance will begin. If the diagnostic test is positive; the contact will be considered a case and will be handled as such. If the diagnostic test is negative; and it is done at any time prior to 10 days after the last contact; quarantine must be fulfilled until day 10; 15/02/2021: Any person with suspected infection will undergo a diagnostic test within the first 24 hours. If the PDIA is negative and there is a high clinical-epidemiological suspicion of COVID-19; it is recommended to repeat the test. If a rapid antigen detection test was initially performed; a PCR will be performed. If a PCR was performed initially; the PCR will be repeated at 48 hours; 16/07/2021: same as before; 22/12/2021: In the event of any suspicious case; it is indicated to begin the identification of their close contacts. The identification of the rest of the close contacts (not living together) may be delayed until the case is classified as a confirmed; provided that said confirmation can be guaranteed within 24-48 days; 30/12/2021: the identification of close contacts will only be carried out in those areas in which exposure is considered high risk due to the presence of people with greater vulnerability; such as health centers and nursing homes or other socio-health centers; 25/03/2022: Close contacts in vulnerable settings will be indicated for PDIA at 3-5 days of follow-up.