The person exposed or suspected of having Covid-19 should be isolated before getting tested and before test results come back to protect others in the home, said the study, published Friday in the CDC's Morbidity and Mortality Weekly Report.
"Because prompt isolation of persons with COVID-19 can reduce household transmission, persons who suspect that they might have COVID-19 should isolate, stay at home, and use a separate bedroom and bathroom if feasible," wrote a CDC-led team of researchers.
In addition, all members of the household should wear masks at all times in common spaces, the team said.
Infection of others happened within days
The research, part of an ongoing CDC-supported study, followed 101 people initially infected with Covid-19 in Nashville, Tennessee, and Marshfield, Wisconsin, between April and September.
Along with some 191 others who lived in their households, the infected people were trained to self-collect specimens -- nasal swabs only or nasal swabs and saliva samples -- each day for 14 days. In addition, each person completed a symptom diary.
Infection was quick: Over half of the people (53%) who lived with someone battling Covid-19 became infected within a week, researchers found. Some 75% of these secondary infections occurred within five days of the first symptoms in the initial patient.
"Substantial transmission occurred whether the index patient was an adult or a child," researchers said.
A 53% household infection rate, the study said, is higher than what has been documented so far. To date, related research has reported only a 20% to 40% infection rate.
"An important finding of this study is that fewer than one half of household members with confirmed SARS-CoV-2 infections reported symptoms at the time infection was first detected," the study authors wrote.
"Many reported no symptoms throughout 7 days of follow-up, underscoring the potential for transmission from asymptomatic secondary contacts and the importance of quarantine."
Isolate yourself or your loved one
Staying isolated from other household members can be challenging, especially if you are in a small space or there are children in the home.
"If you have somebody at home who's older or immunocompromised, you may want to isolate them to one side of the house so the kids and everybody else aren't around them on a regular basis," said pediatrician Dr. Tanya Altmann, editor in chief of the American Academy of Pediatrics' book "Caring for Your Baby and Young Child: Birth to Age 5 and The Wonder Years," in a prior interview.
"If it's a child that you have to care for, then you may have to make the decision to isolate one adult with the child," she added. "That adult would be caring for the child, and the other adult would be responsible for the rest of family."
And of course, all of this will be extremely difficult for a single parent "who might be the only one," said pediatrician Dr. Jenny Radesky, a spokesperson for the American Academy of Pediatrics, in a prior interview.
"Know who your neighbors are, even what your
