COVID-19 not very infectious 8 days after symptoms occur, Winnipeg study suggests

National Institute of Allergy and Infectious Disease

Date Published: May 26, 2020

Source: CBC

Researchers from the National Microbiology Laboratory, Cadham Provincial Laboratory and the University of Manitoba concluded in a recent study that COVID-19 is infectious only for the first 8 days after symptom-onset. The study looked at nasal or throat samples from 90 people in Manitoba who tested positive for COVID-19. The researchers then tried to grow more of the virus from these samples in cell culture, which can be used to predict whether a patient can still infect someone else. They were only able to grow the virus with 26/90 of the samples; there was no viral growth for those samples that were taken from patients more than 8 days after they developed symptoms. Other studies have also reached similar conclusions about COVID-19 being infectious for only 8 days after symptom-onset, and more studies need to be done with larger samples. According to the study, their results have implications for clinical care, public health, and preventing and controlling infection. As the study offers a better definition of the period of maximal transmission risk, the results could also be used to help with case-finding. 

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Summary by: Christina Blagojevic