1 figure omitted
On April 29, 2003, this report was posted on the MMWR
website (http://www.cdc.gov/mmwr). Before publication
in this issue an error was corrected. In the last sentence of the second paragraph
and in the § footnote of the box, the correct number of days should have
been "≤21 days."
CDC's interim surveillance case definition for severe acute respiratory
syndrome (SARS) has been updated to include laboratory criteria for evidence
of infection with the SARS-associated coronavirus (SARS-CoV) (Figure, see
sidebar). In addition, clinical criteria have been revised to reflect the possible spectrum of respiratory
illness associated with SARS-CoV. Epidemiologic criteria have been retained.
The majority of U.S. cases of SARS continue to be associated with travel (see
footnote), with only limited secondary spread to household members or health-care
SARS has been associated etiologically with a novel coronavirus, SARS-CoV.2,3 Evidence of SARS-CoV infection
has been identified in patients with SARS in several countries, including
the United States. Several new laboratory tests can be used to detect SARS-CoV.
Serologic testing for coronavirus antibody can be performed by using indirect
fluorescent antibody or enzyme-linked immunosorbent assays that are specific
for antibody produced after infection. Although some patients have detectable
coronavirus antibody during the acute phase (i.e., within 14 days of illness
onset), definitive interpretation of negative coronavirus antibody tests is
possible only for specimens obtained >21 days after onset of symptoms. A reverse
transcriptase polymerase chain reaction (RT-PCR) test specific for viral RNA
has been positive within the first 10 days after onset of fever in specimens
from some SARS patients, but the duration of detectable viremia or viral shedding
is unknown. RT-PCR testing can detect SARS-CoV in clinical specimens, including
serum, stool, and nasal secretions. Finally, viral culture and isolation have
both been used to detect SARS-CoV. Absence of SARS-CoV antibody in serum obtained
≤21 days after illness onset, a negative PCR test, or a negative viral
culture does not exclude coronavirus infection.
Reported U.S. cases of SARS still will be classified as suspect or probable;
however, these cases can be further classified as laboratory-confirmed or -negative if laboratory data are available and complete, or as laboratory-indeterminate
if specimens are not available or testing is incomplete. Obtaining convalescent
serum samples to make a final determination about infection with SARS-CoV
No instances of SARS-CoV infection have been detected in persons who
are asymptomatic. However, data are insufficient to exclude the possibility
of asymptomatic infection with SARS-CoV and the possibility that such persons
can transmit the virus. Investigations of close contacts and health-care workers
exposed to SARS patients might provide information about the occurrence of
asymptomatic infected persons. Similarly, the clinical manifestations of SARS
might extend beyond respiratory illness. As more is learned about SARS-CoV
infection, clinical and laboratory criteria will provide a framework for classifying
the full spectrum of infection.
This surveillance case definition should be used for reporting and classification
purposes only. It should not be used for clinical management or as the only
criterion for identifying or testing patients who might have SARS or for instituting
infection-control precautions.4,5 This
definition will be updated as new data become available or if changes in the
epidemiology of SARS occur in the United States.
Footnote: In this updated case definition,
Taiwan has been added to the areas with documented or suspected community
transmission of SARS; Hanoi, Vietnam is now an area with recently documented
or suspected community transmission of SARS.
Updated Interim Surveillance Case Definition for Severe Acute Respiratory Syndrome (SARS)—United States, April 29, 2003. JAMA. 2003;289(20):2637-2639. doi:10.1001/jama.289.20.2637-a