Based on new data about how long patients with coronavirus disease 2019 (COVID-19) are likely to remain infectious, the Centers for Disease Control and Prevention (CDC) says that a shorter period of self-isolation than previously advised is needed after a person tests positive for COVID-19. Other new evidence for adults with COVID-19 who recover at home indicates that full recovery may take weeks, even for younger, previously healthy adults.
The CDC notes that accumulating evidence supports using a strategy for ending isolation and precautions for persons with COVID-19 based on symptoms. Previously, the agency used a test-based strategy—recommending that individuals testing positive isolate themselves until they had 2 negative swabs for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)—but such advice proved not to be feasible because of the shortage of tests.
“This update incorporates recent evidence to inform the duration of isolation and precautions recommended to prevent transmission of SARS-CoV-2 to others, while limiting unnecessary prolonged isolation and unnecessary use of laboratory testing resources,” the CDC says.
The updated guidance, reflecting improved understanding of when infected individuals can spread viable virus, says that most people who are symptomatic with COVID-19 should isolate at home for 10 days after symptoms begin and for 24 hours after their fever has broken (without the use of fever-reducing medications) and other symptoms have improved. In patients with mild to moderate COVID-19, virus capable of replicating has not been found after 10 days following the onset of symptoms, the agency notes.
People who test positive for SARS-CoV-2 but never develop symptoms also should isolate for 10 days from the date of their first positive test, the CDC advises.
However, “a limited number of persons with severe illness” and those who are immunocompromised may need to isolate for 20 days after symptom onset, the CDC cautions. Researchers reported being able to recover coronavirus capable of infecting others up to 20 days after symptom onset in some individuals with severe COVID-19, who in some cases also had a weakened immune system.
The agency also released new findings that COVID-19 can result in prolonged illness, even among previously healthy young adults with no underlying chronic medical conditions.
The study involved a multistate telephone survey of adults with COVID-19 symptoms who had a positive outpatient test result for SARS-CoV-2. Among the 270 individuals with available data on when they returned to their usual level of health, 95 (35%) reported they had not done so when interviewed 2 to 3 weeks after testing.
The proportion who had not fully recovered within 14 to 21 days after a positive result increased across age groups. About a quarter of interviewees aged 18 to 34 years, one-third of interviewees aged 35 to 49 years, and nearly half of those 50 years or older reported not returning to their usual level of health within that period. Even among the youngest and healthiest group—individuals 18 to 34 with no chronic medical conditions—9 of 48 (19%) had not fully recovered, the CDC notes, “potentially leading to prolonged absence from work, studies, or other activities.”
Both older age and the presence of multiple chronic medical conditions were associated with prolonged illness in this outpatient population.
The symptoms most likely to linger included cough and fatigue. Among 90 individuals who had shortness of breath at the time of testing, 26 (29%) still had this symptom 2 to 3 weeks later.
The report compared this slow recovery to recovery from influenza: more than 90% of outpatients with the flu recover within about 2 weeks of getting a positive test result.
“Public health messaging should target populations that might not perceive COVID-19 illness as being severe or prolonged, including young adults and those without chronic underlying medical conditions,” the report says. The agency recommends strongly encouraging such preventive measures as frequent handwashing, social distancing, and consistent and correct use of face coverings in public.
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