COVID-19 Most Transmissible 2 Days Before, 3 Days After Symptoms Appear: Study
Beijing: People infected with the SARS-CoV-2 virus, which causes COVID-19, are most contagious two days before, and three days after they develop symptoms, according to a study conducted in China. The researchers conducted contact tracing and studied COVID-19 transmission among approximately 9,000 close contacts of primary cases in the Zhejiang province of China from January 2020 to August 2020. Of the individuals identified as primary cases, 89 per cent developed mild or moderate symptoms, and only 11 per cent were asymptomatic — and no one developed severe symptoms. However, regardless of these risk factors, close contacts were more likely to contract COVID-19 from the primary infected individual if they were exposed shortly before or after the individual developed noticeable symptoms. In comparison to mild and moderate symptomatic individuals, asymptomatic primary individuals were much less likely to transmit COVID to close contacts — but if they did, the contacts were also less likely to experience noticeable symptoms, the researchers said.
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