- The CDC defines “close contact” as (a) being within approximately 6 feet of a COVID-19 case for more than a few minutes; close contact can occur while caring for, living with, visiting, or sharing a health care waiting area or room with a COVID-19 case; OR (b) having direct contact with infectious secretions of a COVID-19 case (e.g., being coughed on).
- Any patient who has had “close contact” with a person confirmed to have, or being evaluated for, COVID-19 infection, should immediately seek care from a healthcare professional and/or notify their local health department.
Uses nucleic acid-amplification technology (e.g., PCR), which detects the genetic information and indicates active infection with the virus which causes COVID-19.
A negative test result for this test means that SARS-CoV-2 RNA was not detected in the specimen. However, a negative result does not completely rule out COVID-19 and should not be used as the sole basis for treatment or patient management decisions. When diagnostic testing is negative, the possibility of a false negative result should be considered in the context of any recent exposure and clinical signs or symptoms that may suggest COVID-19. The possibility of a false negative result should especially be considered if COVID-19 is clinically likely and diagnostic tests for other causes of illness (e.g., other respiratory illness) are negative. If COVID-19 is still suspected, re-testing should be considered by healthcare providers in consultation with public health authorities.
A positive test result indicates that SARS-CoV-2 RNA was detected, and the patient is presumably infected with the virus and presumably contagious. Laboratory test results should be considered in the clinical and community context to establish a final diagnosis and care plan. Positive results do not rule out simultaneous bacterial infection or co-infection with other viruses. Patient management decisions should be made by a healthcare provider and should follow the current CDC guidelines. The COVID-19 test has been designed to minimize the likelihood of false-positive test results, but it may not be possible to completely exclude a false positive.
Serology testing can check for different types of antibodies developed after exposure to the SARS-CoV-2 virus that causes COVID-19. Unlike PCR tests, serology tests by themselves, are of limited value in the immediate diagnosis of a patient where COVID-19 infection is suspected.
The test is designed to detect antibodies in a blood sample that would indicate that you have been previously infected by SARS-CoV-2 virus. However, antibodies may not be detected until 10-14 days following infection.
Serology tests may detect different types of antibodies. A positive result from an appropriately validated serology test indicates that someone currently has or has previously had COVID-19. However, a serology may yield a negative test result even in infected patients (e.g., if antibody has not yet developed in response to the virus) or may be falsely positive (e.g., if antibody to a coronavirus type other than the current pandemic novel strain is present). Antibody tests by themselves cannot establish the immediate diagnosis of COVID-19. Serology testing cannot detect or rule out presence of the virus.
Serology tests, when used broadly, can also be useful in understanding how many people have been infected or exposed and how far the pandemic has progressed.
Using this type of test on many patients may help the medical community to better understand how the immune response against the SARS-CoV-2 virus develops in patients over time and may provide guidance in infection control, exposure risk assessment, social distancing, and other population surveillance and preventive efforts.
Serology tests can play a critical role in the fight against COVID-19 by helping healthcare professionals identify individuals who have been exposed to SARS-CoV-2 virus. In the future, this may potentially be used to help determine, together with other clinical data, whether these individuals may be less susceptible to infection. In addition, these test results can aid in determining who may donate convalescent plasma for possible treatment of those who are seriously ill from COVID-19.