Probable SARS Inclusion Criteria: 1. One of the following: Travel within 10 days of onset of symptoms to an area with documented or suspected community transmission of SARS (as continually defined by the WHO and/or CDC) OR Close contact within 10 days of onset of symptoms with a person known to be a suspect SARS case. Close contact is defined as having cared for, having lived with, or having direct contact with respiratory secretions and/or body fluids of a patient known to be suspect SARS case. AND 2. Measured temperature greater than 100.4(Degree)F (greater than 38(Degree) C) AND 3. Evidence of an acute respiratory illness as manifested by one of the following: Cough: shortness of breath, difficulty breathing, hypoxia AND 4. Radiographic evidence of pneumonia or ARDS AND 5. Clinically stable for transfer to the Clinical Center AND 6. The ability to understand and willingness to sign a written consent form or in cases of 1) a minor, 2) temporary incompetence due to severe illness, or 3) permanent incompetence due to a chronic condition, informed consent may be signed by a legal guardian or appropriate proxy. Suspected SARS Inclusion Criteria: 1. One of the following: 1. Travel within 14 days of onset of symptoms to an area with documented or suspected community transmission of SARS (as continually defined by the WHO and/or CDC) OR 2. Close contact within 14 days of onset of symptoms with either a person with a respiratory illness who traveled to a SARS area or a person known to be a suspect SARS case. Close contact is defined as one of the following: Close contact is defined as having cared for, having lived with, or having direct contact with respiratory secretions and/or body fluids of a patient known to be suspect SARS case. Other contact of sufficient proximity and duration that transmission of the causative agent of SARS may have occurred. This will be determined on an individual basis by the PI or an associate investigator. AND 2. One of the following: 1. Measured temperature greater than 100.4(Degree)F (greater than 38(Degree) C) 2. Evidence of an acute respiratory illness as manifest by one of the following: cough, shortness of breath, difficulty breathing, hypoxia, radiographic findings of either pneumonia or acute respiratory distress syndrome AND 3. Clinically stable for transfer to the Clinical Center AND 4. The ability to understand and willingness to sign a written consent form or in cases of 1) a minor, 2) temporary incompetence due to severe illness, or 3) permanent incompetence due to a chronic condition, informed consent may be signed by a legal guardian or appropriate proxy. Close Contact Inclusion Criteria: 1. Close contact with a patient suspected to have SARS within 10 days of the time of enrollment. Close contact is defined as one of the following: having cared for, having lived with, or having direct contact with respiratory secretions and/or body fluids of a patient suspected or known to have SARS. Other contact of sufficient proximity and duration that transmission of the causative agent of SARS may have occurred. This will be determined on an individual basis by the PI or an associate investigator. AND 2. The ability to understand and willingness to sign a written consent form or in cases of 1) a minor, 2) temporary incompetence due to severe illness, or 3) permanent incompetence due to a chronic condition, informed consent signed by a legal guardian or appropriate proxy. Recovered SARS Inclusion Criteria 1. Within the last six months, had one of the following: 1. an acute illness characterized by (all of the following): 1. Fever greater than 100.4 (if measured) AND 2. History of an acute respiratory illness as manifested by one of the following: cough, shortness of breath, difficulty breathing, hypoxia AND 3. The illness occurred within 10days of travel to an area with documented or suspected community transmission of SARS (as continually defined by the WHO and/or CDC) OR Had close contact within 10 days of onset of symptoms with either a person with a respiratory illness who traveled to a SARS area or a person known to be a suspected SARS case. Close contact is defined as one of the following: Close contact is defined as having cared for, having lived with, or having direct contact with respiratory secretions and/or body fluids of a patient known to be suspect SARS case. Other contact of sufficient proximity and duration that transmission of the causative agent of SARS may have occurred. This will be determined on an individual basis by the PI or an associate investigator. OR 2. an acute respiratory illness with the laboratory confirmation of SARS AND 2. The ability to understand and willingness to sign a written consent form or in cases of 1) a minor, 2) temporary incompetence due to severe illness, or 3) permanent incompetence due to a chronic condition, informed consent signed by a legal guardian or appropriate proxy. Health Care Worker Surveillance Inclusion Criteria 1. NIH health care worker that is anticipated to be involved with the clinical care of SARS patients 2. The ability to understand and willingness to sign a written consent form. A health care worker is defined as anyone involved with patient care or patient contact. Note: this group may be enrolled prior to SARS patients hospitalized at the clinical center.

Probable SARS Exclusion Criteria: 1. Age less than 18 years old. 2. Known pregnancy or positive urine/blood pregnancy test. Suspected SARS Exclusion Criteria: 1. Meets inclusion criteria for SARS 2. Age less than 18 years old. 3. Known pregnancy or positive urine/blood pregnancy test. Close Contact Exclusion Criteria: 1. Less than 10 kg. 2. Subjects who meet criteria for SARS or Suspected SARS Recovered SARS Exclusion Criteria 1. Less than 10 kg. 2. Temperature greater than 100.4 F (38.0 C) or symptoms of active respiratory illness Health Care Worker Surveillance Exclusion Criteria No exclusion criteria.