Some recovered Covid-19 patients may still carry virus, says study

It found that Covid-19 patients who continued to have respiratory symptoms, especially sore throat and rhinitis, were more likely to have a new positive test result

Some recovered Covid-19 patients may still carry the novel coronavirus, according to a new study which recommends that people leaving quarantine avoid close contact with others, wear a face mask, and possibly undergo an additional test to confirm if they are free of the virus.

The study, assessed 131 Covid-19 patients who met the World Health Organization (WHO) criteria for discontinuation of quarantine, and found that close to 17 per cent of them, who were considered fully recovered, tested positive for the virus in follow-up screening.

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"Our findings indicate that a noteworthy rate of recovered patients with Covid-19 could still be asymptomatic carriers of the virus," said study co-author Francesco Landi from Fondazione Policlinico Universitario in Italy.

In the study, the researchers followed Covid-19 patients after their recovery to assess the impact of the virus on their bodies.

It found that patients who continued to have respiratory symptoms, especially sore throat and rhinitis, were more likely to have a new positive test result.

The researchers said the persistence of these two symptoms should not be underestimated and must 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," Landi explained.

In the study, the researchers assessed 131 patients who met the WHO criteria for discontinuation of quarantine.

It specifies that patients should be fever-free without fever-reducing medications for three days, show improvement in any symptoms related to COVID-19, and be more than seven days past symptom onset.

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According to the WHO criteria, the patients must also test negative for the SARS-CoV-2 virus twice, at least 24 hours apart, with reverse transcription PCR (RT-PCR) testing.

The scientists also collected demographic, medical, and clinical information from the patients 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.

Their analysis found that twenty-two (16.7 per cent) of the patients tested positive again.

The study did not find any significant difference between patients with positive and negative test results in terms of age or sex.

It noted that none of the patients had fever and all reported improvement in their overall clinical condition.

According to the researchers, the time since onset of disease, number of days hospitalised, and treatments received while receiving care were not significant.

However, they said some symptoms such as fatigue (51 per cent), laboured breathing (44 percent) and coughing (17 percent) were still present in a significant percentage of the patients studied.

But the scientists added that there were no significant differences between individuals with a positive or negative test.

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The only two symptoms that were higher and significantly prevalent in patients with a positive test were sore throat and signs of rhinitis, they said.

"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," Landi said.

The scientists explained that the RT-PCR test looks for small fragments of viral genetic material, it's RNA, and 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," Landi added.

For patients who continue to have symptoms potentially related to Covid-19, the researchers said it is reasonable to be cautious and avoid close contact with others, wear a face mask, and possibly undergo an additional nasopharyngeal swab.