The Centers for Disease Control and Prevention acknowledged Friday that a significant number of COVID-19 patients do not recover quickly, and instead experience ongoing symptoms, such as fatigue and cough.
As many as a third of patients who were never sick enough to be hospitalized are not back to their usual health up to three weeks after their diagnosis, the report found.
"COVID-19 can result in prolonged illness even among persons with milder outpatient illness, including young adults," the report's authors wrote.
The acknowledgement is welcome news to patients who call themselves "long-haulers" — suffering from debilitating symptoms weeks and even months after their initial infection.
"This report is monumental for all of us who have been struggling with fear of the unknown, lack of recognition and many times, a lack of belief and proper care from medical professionals during our prolonged recovery from COVID-19," Kate Porter, who is on day 129 of her recovery, wrote in an email to NBC News.
Porter, 35, of Beverly, Massachusetts, has had low-grade fevers, fatigue, rapid heart beat, shortness of breath and memory and sleep issues since her diagnosis March 17.
"This gives me hope that we will gain access to more resources throughout our recovery and hopefully, get our lives back to what they once were," Porter wrote.
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The CDC report is based on telephone surveys of 274 COVID-19 patients. Ninety-five of those patients, or 35 percent, said they "had not returned to their usual state of health" when they were surveyed, which was at least two to three weeks after their first test.
Many with long-term symptoms are otherwise young and healthy: Among those surveyed between ages 18 and 34, about 20 percent experienced lasting symptoms.
"This report indicates that even among symptomatic adults tested in outpatient settings, it might take weeks for resolution of symptoms and return to usual health," the CDC authors wrote.
The report also pointed out that in contrast, "over 90 percent of outpatients with influenza recover within approximately two weeks" after a positive flu test.
Among the patients who experienced lasting symptoms in the CDC report, 71 percent reported fatigue, 61 percent had lasting cough, and 61 percent reported ongoing headaches.
The CDC added that preventative measures, such as physical distancing, face masks and frequent hand-washing, continue to be important to slow the spread of COVID-19.