Contact Tracing Assessment of COVID-19 Transmission Dynamics in Taiwan and Risk at Different Exposure Periods Before and After Symptom Onset | Global Health | JAMA Internal Medicine | JAMA Network

The 299 contacts with exclusive presymptomatic exposures were also at risk (attack rate, 0.7% [95% CI, 0.2%-2.4%]). 

https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2765641

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