May 4, 2020 - Health

Coronavirus patients are most infectious early on

People wait in line for free masks in New York City.

Photo: Michael Nagle/Xinhua via Getty Images

Coronavirus patients are most likely to infect other people in the early stages of the disease, even before they start showing symptoms, according to a new study in JAMA Internal Medicine.

Why it matters: This can help inform public health officials' efforts to trace and isolate a confirmed patients' known contacts.

  • It also means that stopping the spread of the virus will be challenging, as people are most contagious before they may even know they have the virus.

Details: The study, which focused on confirmed coronavirus patients in Taiwan and their contacts, found that the novel coronavirus has a relatively short infectious period.

  • The risk of transmission is highest around the time a patient becomes symptomatic, and decreases with time.
  • "Because the onset of overt clinical symptoms, such as fever, dyspnea, and signs of pneumonia, usually occurred 5 to 7 days after initial symptom onset, the infection might well have been transmitted at or before the time of detection," the authors write.

Go deeper: The good and bad news about asymptomatic coronavirus cases

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