Even Those Who Just Test Positive at More Risk for Long COVID: CDC

Marcia Frellick

September 09, 2021

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Long-term symptoms, like those linked with COVID-19, were common in people who  had even just a single positive test, new Centers for Disease Control and Prevention (CDC) data show.

The data show that symptoms in this group — including fatigue, cough, and headache — tended to last for more than a month. 

Frequency of symptoms in people with a positive test was 1.5 times higher compared with people whose tests had always been negative, according to the research published Thursday in the CDC's latest Morbidity and Mortality Weekly Report.

Lead author Valentine Wanga, PhD, with the CDC's COVID-19 response team, and colleagues conducted a nonprobability-based internet panel survey of about 6000 US adults to assess long-term symptoms often associated with COVID-19 among those who had ever tested positive or always tested negative for COVID-19 between January 2020 and April 2021.

William Schaffner, MD, an infectious disease expert at Vanderbilt University in Nashville, Tennessee, told Medscape Medical News, that this research "establishes more securely than before that you don't have to be hospitalized with COVID in order to develop long COVID symptoms."

That's better known among infectious disease experts, he said, but added that "this survey really gives a firm database for that."

Study Results

The study's results showed that, compared with respondents who had a negative test result, those who received a positive result reported a significantly higher prevalence of any long-term symptom (65.9% vs 42.9%); fatigue (22.5% vs 12.0%); change in sense of smell or taste (17.3% vs 1.7%); shortness of breath (15.5% vs 5.2%); cough (14.5% vs 4.9%); and headache (13.8% vs 9.9%).

More people who had a positive test result (76.2%) reported persistence for more than a month of at least one initially occurring symptom compared with those whose test results were always negative (69.6%).

The numbers are further proof, Schaffner said, that COVID not only will be an acute stressor on the healthcare system but patients with long COVID will need help with managing care for the long term.

"We still don't know what the COVID virus does that results in these long COVID symptoms," he said. Vanderbilt and many other institutions have developed 'long COVID' centers as a testament to how important the problem is, he noted.

Long COVID symptoms are not well understood and most studies have looked at the effects from patients who had been hospitalized with COVID-19.

In this survey, respondents self-reported whether they had ever had a positive SARS-CoV-2 test result (698), always received a negative test result (2437), or never were tested for SARS-CoV-2 (2750).

Compared with those who always tested negative, a larger proportion of those who tested positive (28.7% vs 15.7%) reported believing that receiving a COVID-19 vaccine made their long-term symptoms better. No difference was found in reported beliefs that a vaccine made long-term symptoms worse.

Schaffner said he found that survey result interesting, but said that is not backed up by current data and would need further study.

"I would treat that with great caution," he said. "I'm not dismissing it, but you can't take that at face value. All of us who get sick and those of us who care for people who are sick — if there's an intervention, we all hope for the best. We're being optimistic. It's when you do a randomized, double-blind, placebo-controlled study that you can find out whether your instincts or hopes were correct."

The authors say findings can inform public health preparedness, help guide care for people with post-COVID conditions, and help make the case for vaccines.

The study authors and Schaffner have disclosed no relevant financial relationships.

Marcia Frellick is a freelance journalist based in Chicago. She has previously written for the Chicago Tribune, Science News, and Nurse.com, and was an editor at the Chicago Sun-Times, the Cincinnati Enquirer, and the St. Cloud (Minnesota) Times. Follow her on Twitter at @mfrellick


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