Earlier this month, the US Centers for Disease Control and Prevention released guidance to shorten the 14-day Covid-19 quarantine to seven to 10 days. However, in its Morbidity and Mortality Weekly Report, the CDC concludes that this move "carries a risk" to further spread the virus, particularly the risk posed by household contacts.
Interim data from a CDC-supported study of household transmission of Covid-19, showed that among 185 people who lived in households with someone who was sick with Covid-19, 109 of them ended up getting Covid-19 themselves.
Of those 109 people, 76% tested positive within seven days after the person they were living with first felt sick, and 86% tested positive within 10 days after the person they were living with first felt sick. This shows that there is a potential for transmission of the virus from household contacts released from quarantine before 14 days, according to the report.
Household contacts who tested negative for the virus and were without symptoms through day seven had an 81% chance of remaining symptom free and testing negative through day 14.
But that means one in five people still became symptomatic or received a positive Covid-19, suggesting that "reducing quarantine to less than 14 days might decrease but not eliminate the risk for spreading" the virus, the report said.