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Coronavirus spreads quickly among household members, CDC report finds

The report noted that the age of the index patient didn’t matter — adults, children and teens all spread the virus to others in their households.
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A woman isolating at home with her family, all positive for Covid-19, looks from her front door on April 16, 2020 in Long Island, New York. John Moore / Getty Images

If one person in a household has Covid-19, there’s a good chance it’ll spread to others — and quickly.

A report from the Centers for Disease Control and Prevention, published Friday, took a close look at how the virus spread throughout people’s homes.

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The study included 101 households in Nashville, Tennessee, and Marshfield, Wisconsin. All households had one index patient — a confirmed case of Covid-19. At the time the index patient first reported symptoms, no one else in their household reported any.

The 101 index patients (each in their own household) lived with a total of 191 household contacts, 102 of whom — or 53 percent — went on to test positive for Covid-19, according to the report.

What’s more, the spread occurred “rapidly,” the authors wrote: “Approximately 75 percent of infections [were] identified within 5 days of the index patient’s illness onset.”

The report noted that the age of the index patient didn’t matter — adults, children and teens all spread the virus to others in their households.

Family clusters were reported to be a source of spread early on in the pandemic. The first instance of person-to-person spread in the country was between a husband and his wife in Chicago. One of the first coronavirus cases in New York, a man in his 50s, spread the virus to his wife and two of his children.

As early as February, the World Health Organization noted that most cases in China occurred in family clusters.

Isolate immediately

The new report highlights the importance of isolating family members as soon as possible if they suspect they have Covid-19.

"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 authors wrote. At the same time, the authors added, everyone in the home should start wearing a mask.

If feasible, the individual should isolate in a separate bedroom and use a separate bathroom.

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The report noted that 69 percent of the index patients, however, reported spending at least four hours in the same room with other household members the day before getting sick, and 40 percent said they spent the same amount of time with others the day after getting sick.

Similarly, 40 percent of the index patients shared a bedroom before getting sick, and 30 percent shared a bedroom after getting sick.

The report also underscored the importance of quarantining. Less than one half of the household contacts who tested positive for the coronavirus had symptoms when they were tested, and many reported no symptoms over the next seven days. These individuals should quarantine to avoid spreading the infection to others.

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