Diagnosis

Infection by the virus can be provisionally diagnosed on the basis of symptoms, though confirmation is ultimately by reverse transcription polymerase chain reaction (rRT-PCR) of infected secretions (71% sensitivity) and CT imaging (98% sensitivity).[396]

Viral testing

The WHO has published several RNA testing protocols for SARS-CoV-2, with the first issued on 17 January.[397][398][399] Testing uses real-time reverse transcription polymerase chain reaction (rRT-PCR).[400] The test can be done on respiratory or blood samples.[401] Results are generally available within a few hours to days.[402][403]

A person is considered at risk if they have travelled to an area with ongoing community transmission within the previous 14 days, or have had close contact with an infected person. Common key indicators include fever, coughing and shortness of breath. Other possible indicators include fatigue, myalgiaanorexiasputum production and sore throat.[404]

Imaging

Characteristic imaging features on radiographs and computed tomography of symptomatic patients include asymmetric peripheral ground glass opacities and absent pleural effusions.[405] The Italian Radiological Society is compiling an international online database of imaging findings for confirmed cases.[406] Due to overlap with other infections such as adenovirus, imaging without confirmation by PCR is of limited specificity in identifying COVID-19.[405] However, a large study in China compared chest CT results to PCR and demonstrated that though imaging is less specific for the infection, it is faster and more sensitive, suggesting its consideration as a screening tool in epidemic areas.[407]