COVID-19: An infected person may infect others till 22 days

A person infected with novel coronavirus (SARS-CoV-2) may ‘shed’ or expel the virus till 20 days of infection and the non-survivors of the disease, COVID-19, can do so till their death, according to a paper published in The Lancet journal.

The authors, including those from the Chinese Academy of Medical Sciences and other institutes of China, said this duration might be longer than what was expected.

The range of the viral shedding period is 8-37 days, with an average of 20 days. This means that an infected person can shed the virus or infect anybody till 20 days of the onset of symptoms.

For the Severe Acute Respiratory Syndrome or SARS coronavirus, this period was about four weeks and for the Middle East Respiratory Syndrome or MERS infection, three weeks.

The authors of this paper said that treatment for COVID-19 with antiviral drugs improved a patient’s treatment outcomes but did not decrease the viral load shedding period. The authors did not study the load shedding period with lopinavir / ritonavir, the two drugs that are being studied as potential drugs for the disease.

“This (viral shedding period) has important implications for both, patient isolation decision making and guidance around the length of antiviral treatment. In severe influenza virus infection, prolonged viral shedding was associated with fatal outcome and delayed antiviral treatment was an independent risk factor for prolonged virus detection,” the authors wrote.

“We recommend that negative tests for COVID-19 should be required before patients are discharged from hospital. In severe influenza, delayed viral treatment extends how long the virus is shed, and together, these factors put infected patients at the risk of dying,” lead author Bin Cao from the China-Japan Friendship Hospital and Capital Medical University, China, said. 

The median time from illness onset to discharge was found to be 22 days. The average time from onset to death was 18.5 days. Of the 191 patients enrolled, 32 required ventilation. And, of these 32 patients, 31 died. 

The median time from illness onset to ventilation was 14.5 days. Three of 191 patients required extracorporeal membrane oxygenation, a support which helps circulate blood from the lungs to the bloodstream. None of these patients survived. 

Sepsis was the most frequent complication of those who died, followed by respiratory failure, heart failure and septic shock. 

Even device-associated infections were observed in those who required ventilators. Thirty-one patients required ventilation and 10 of them developed ventilator-associated pneumonia. Other secondary infections were also observed. 

The median time from illness onset to shortness of breath was similar in survivors and non-survivors 13 days. In survivors, the median duration of fever was 12 days and cough persisted for 19 days. 

As many as 45 per cent survivors still had a cough on discharge. Shortness of breath, cough and fever are classical symptoms of the disease. 

This study also reinforced the fact that increased age was associated with death in patients with COVID-19. The total global tally reached to 114,809 with 4,031 deaths on March 10, 2020. The total number of countries affected is now 115. 

In India, six new cases from Kerala and three more Karnataka tested positive for the virus on March 10, 2020. Two cases were confirmed in Pune on March 9. With this, the total count of COVID-19 has gone up to 56. No death has been reported from the country so far.

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