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خرید پکیج
تعداد آیتم قابل مشاهده باقیمانده : 3 مورد
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Diagnostic tests for COVID-19[1,2]

Diagnostic tests for COVID-19[1,2]
Test category Primary clinical use Specimen type Performance characteristics Comments
NAATs (including RT-PCR) Diagnosis of current infection Respiratory tract specimens*
  • High analytic sensitivity and specificity in ideal settings.
  • Clinical performance depends on the type and quality of the specimen and the duration of illness at the time of testing.
  • Reported false-negative rate ranges from <5 to 40%, depending on the test used.
  • Time to perform the test ranges from 15 minutes to 8 hours.Δ
  • Turnaround time is influenced by the test used and laboratory workflow.
  • Some assays allow home collection of specimens that are mailed in.
Serology (antibody detection) Diagnosis of prior infection (or infection of at least 3 to 4 weeks' duration) Blood
  • Sensitivity and specificity are highly variable.
  • Detectable antibodies generally take several days to weeks to develop; IgG usually develops by 14 days after onset of symptoms.
  • Cross-reactivity with other coronaviruses has been reported.
  • Individual results should be interpreted with caution in settings of low seroprevalence; serologic tests that have high specificity still have a low positive predictive value.
  • Time to perform the test ranges from 15 minutes to 2 hours.
  • Turnaround time is influenced by the test used and laboratory workflow.
  • It remains uncertain whether a positive antibody test indicates immunity against future infection.
Antigen tests Diagnosis of current infection Nasopharyngeal or nasal swabs
  • Antigen tests are generally less sensitive than nucleic acid tests.
  • Sensitivity is highest in symptomatic individuals within 5 to 7 days of symptom onset.
  • Time to perform the test is <1 hour.

COVID-19: coronavirus disease 2019; NAAT: nucleic acid amplification test; RT-PCR: reverse transcription polymerase chain reaction; IgG: immunoglobulin G; CDC: United States Centers for Disease Control and Prevention.

* Nasopharyngeal swabs, nasal swabs (from the midturbinate area or from both anterior nares), nasal or nasopharyngeal washes, oropharyngeal swabs, and saliva are recommended by the CDC. The Infectious Diseases Society of America suggests a nasopharyngeal swab, a midturbinate swab, an anterior nasal swab, saliva, or a combined anterior nasal/oropharyngeal swab rather than an oropharyngeal swab. Nasal swabs can be self-collected by the patient on-site or at home. Midturbinate swabs and saliva can be collected by the patient while supervised. Lower respiratory tract specimens can be collected in hospitalized patients with suspected lower respiratory tract infection if an upper respiratory tract specimen tests negative.

¶ A single positive test generally confirms the diagnosis. If initial testing is negative and clinical suspicion remains, performing a second test can enhance diagnostic yield.

Δ Low-complexity rapid tests can be performed at the point of care and provide results in less than 1 hour. Most moderate- to high-complexity laboratory-based tests result in several hours. However, the time for a clinician or patient to receive a result depends on how frequently the test is run and other processing factors.
References:
  1. Cheng MP, Papenburg J, Desjardins M, et al. Diagnostic Testing for Severe Acute Respiratory Syndrome-Related Coronavirus 2: A Narrative Review. Ann Intern Med 2020; 172:726.
  2. Weissleder R, Lee H, Ko J, Pittet MJ. COVID-19 Diagnostics in Context. Sci Transl Med 2020; 12:eabc1931.
Graphic 128419 Version 8.0

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