U.S. health officials Wednesday redefined what counts as close contact with someone who has COVID-19 to include briefer but repeated encounters.
For months, the U.S. Centers for Disease Control and Prevention said close contact meant spending a solid 15 minutes within six feet or two metres of someone who tested positive for coronavirus. On Wednesday, the CDC changed that to a total of 15 minutes or more — so shorter but repeated contacts that add up to 15 minutes over a 24-hour period now count as close contact.
The CDC advises anyone who has been in close contact with a COVID-19 patient to quarantine for two weeks.
The change may prompt health departments to do contact tracing in cases where an exposure might previously have been considered too brief, said Dr. William Schaffner, a Vanderbilt University infectious diseases expert.
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It’s also serves notice that the coronavirus can spread more easily than many people realize, he said.
The definition change was triggered by a study of a 20-year-old Vermont correctional officer, who was diagnosed with coronavirus in August.
The guard, who wore a mask and goggles, had multiple brief encounters with six transferred prisoners before test results showed they were positive.
At times, the prisoners wore masks, but there were encounters in cell doorways or in a recreational room where prisoners did not have masks on, the report said.
An investigation that reviewed video footage concluded the guard’s brief interactions totalled 17 minutes during an eight-hour shift.
In a statement, CDC officials said the case again highlights the importance of wearing masks to prevent transmission.