News Release

Close to 17 percent of patients recovered from COVID-19 could still carry virus

Although meeting the criteria for discontinuation of quarantine, patients with persistent respiratory symptoms are more likely to test positive for the virus, finds a new study in the American Journal of Preventive Medicine

Peer-Reviewed Publication


Ann Arbor, October 28, 2020 - A new study in the American Journal of Preventive Medicine, published by Elsevier, presents new data that address important questions pertaining to the containment of the coronavirus pandemic: When should COVID-19 quarantine really end and which continuing symptoms may be more indicative of a positive test in recovered patients?

The study was conducted by the Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy, where a multidisciplinary healthcare service was established for all patients who have recovered from COVID-19 to study what happens to them after recovery and to assess the impact of the virus on their bodies.

Investigators report that close to 17 percent of patients considered fully recovered from COVID-19 tested positive for the virus in follow-up screening. Patients who continued to have respiratory symptoms, especially sore throat and rhinitis, were more likely to have a new positive test result. This suggests the persistence of these two symptoms should not be underestimated and should be adequately assessed in all patients considered recovered from COVID-19.

"Clinicians and researchers have focused on the acute phase of COVID-19, but continued monitoring after discharge for long-lasting effects is needed," explained lead investigator Francesco Landi, MD, PhD, Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, and Catholic University of the Sacred Heart, Rome, Italy.

The study included 131 patients who met the World Health Organization (WHO) criteria for discontinuation of quarantine at least two weeks prior to the follow-up visit. The WHO criteria specify that the patient should be fever-free without fever-reducing medications for three days, show improvement in any symptoms related to COVID-19, be more than seven days past symptom onset, and test negative for the SARS-CoV-2 virus twice, at least 24 hours apart, with reverse transcription PCR (RT-PCR) testing.

A new RT-PCR test was administered at the time of post-acute care admission. Demographic, medical, and clinical information was collected, with an emphasis on the persistence of symptoms and signs related to COVID-19 such as cough, fatigue, diarrhea, headache, smelling disorders, loss of appetite, sore throat, and rhinitis.

Twenty-two (16.7 percent) of the patients tested positive again. There was no significant difference between patients with positive and negative test results in terms of age or sex. None of the patients had fever and all reported improvement in their overall clinical condition. Time since onset of disease, number of days hospitalized, and treatments received while hospitalized were not significant. However, some symptoms such as fatigue (51 percent), labored breathing (44 percent) and coughing (17 percent) were still present in a significant percentage of the patients studied, although there were no significant differences between individuals with a positive or negative test. The only two symptoms that were higher and significantly prevalent in patients with a positive test were sore throat (18 percent vs. 4 percent) and signs of rhinitis (27 percent vs. 2 percent).

Our findings indicate that a noteworthy rate of recovered patients with COVID-19 could still be asymptomatic carriers of the virus," Dr. Landi observed. "The main question for the containment of SARS-CoV-2 pandemic infection that still needs to be answered is whether persistent presence of virus fragments means the patients is still contagious. The RT-PCR test looks for small fragments of viral RNA. A positive swab test can reveal if patients are still shedding viral fragments, but it is not able to discern whether they are or aren't infectious."

Importantly, the investigators recommend that for patients who continue to have symptoms potentially related to COVID-19, it is reasonable to be cautious and avoid close contact with others, wear a face mask, and possibly undergo an additional nasopharyngeal swab.


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