“Approximately 75% of secondary infections were identified within 5 days of the index patient’s illness onset, and substantial transmission occurred whether the index patient was an adult or a child,” the CDC wrote.
Secondary infection rates were high across all racial and ethnic groups, and substantial transmission occurred whether the index patient was an adult or a child.
“Because household transmission of SARS-CoV-2 is common and can occur rapidly after the index patient’s illness onset, persons should self-isolate immediately at the onset of COVID-like symptoms, at the time of testing as a result of a high risk exposure, or at the time of a positive test result, whichever comes first,” the scientists wrote.
Everyone in the home should also wear a mask, especially in shared spaces where distancing isn’t possible.
Isolation of people who test positive for COVID-19 can reduce household transmission, the CDC said, and index patients also should stay home, and use a separate bedroom and bathroom if possible.
“Isolation should begin before seeking testing and before test results become available because delaying isolation until confirmation of infection could miss an opportunity to reduce transmission to others,” the CDC said.
One important finding, the scientists pointed out, is that more than half of the index patients reported having no symptoms when their infection was first detected, and many reported no symptoms during the first seven days of follow-up.