Coronavirus Blackboard

Topic 15: SARS-CoV-2 Shedding and Transmission

Question: A person was diagnosed with COVID-19 a month ago, and his swab test continues to come back positive for the SARS-CoV-2 virus. Is this person likely to be infectious now?  

Answer: No.Experts now think that people whose swab tests show evidence of the virus several weeks after initial diagnosis may not be infectious. 

The swab test for COVID-19 is reported as positive if it shows evidence of proteins from the virus in the sample. This may be virus that can be transmitted or inactive virus that is not infectious. It turns that some people continue to have a positive swab test up to 6 weeks after their initial COVID diagnosis. Research findings are now suggesting that swab tests that remain positive beyond 2 or 3 weeks after initial diagnosis of COVID-19 are unlikely to reflect disease that can be transmitted.

We have learnt similar things from other viruses. Swab tests for COVID-19 that continue to be positive after several weeks need to be interpreted with caution, and should not be assumed to mean the person is infectious.


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