Positive results are indicative of the presence of SARS-CoV-2 RNA; clinical correlation with patient history and other diagnostic information is necessary to determine patient infection status. Positive results do not rule out bacterial infection or co-infection with other viruses. Laboratories within the United States and its territories are required to report all positive results to the appropriate public health authorities.
Negative results do not preclude SARS-CoV-2 infection and should not be used as the sole basis for patient management decisions. Negative results must be combined with clinical observations, patient history, and epidemiological information.
Optimum specimen types and timing for peak viral levels during infections caused by SARS-CoV-2 have not been determined. Collection of multiple specimens from the same patient may be necessary to detect the virus. The possibility of a false negative result should especially be considered if the patient’s recent exposures or clinical presentation suggest that SARS-CoV-2 infection is possible and diagnostic tests for other causes of illness (e.g., other respiratory illness) are negative. If SARS-CoV-2 infection is still suspected, re-testing should be considered in consultation with public health authorities.

Based on literature review and in-house evaluation of saliva samples collected in parallel with nasopharyngeal swabs, saliva approaches, but may not equal, the sensitivity of nasopharyngeal samples for detection of SARS-CoV-2. Therefore, saliva is recommended for use in patients for whom it improves access to SARS-CoV-2 diagnostic testing. In situations where maximum sensitivity is needed for patient care or infection prevention, a nasopharyngeal swab sample is recommended.