Patients infected by the novel coronavirus 2019 shed the virus for 20 days, says a new study that also identifies old age as a key factor for death by COVID19, which sweeps across the globe infecting more than 109,000 and killing nearly 4,000.
The new study is the first for public health researchers to examine the risk factors associated with severe disease and death in hospitalised adults who have either died or been discharged.
In a study published in the Lancet on Monday, Chinese researchers examined 191 patients from two Wuhan hospitals out of whom 137 were discharged whereas 54 died.
The new data suggest the median duration of viral shedding was 20 days in survivors (ranging from 8 to 37 days), and the virus was detectable until death in the 54 non-survivors.
While prolonged viral shedding suggests that patients may still be capable of spreading COVID-19, the authors caution that the shedding duration is influenced by disease severity.
All patients examined in the study were hospitalised and two-thirds of them had severe or critical illness.
“The extended viral shedding noted in our study has important implications for guiding decisions around isolation precautions and antiviral treatment in patients with confirmed COVID-19 infection,” one of the team leaders. Bin Cao from the China-Japan Friendship Hospital and Capital Medical University, China said in a media statement.
“However, we need to be clear that viral shedding time should not be confused with other self-isolation guidance for people who may have been exposed to COVID-19 but do not have symptoms, as this guidance is based on the incubation time of the virus.”
Currently, 14 days of isolation stay is being practised by the nations running quarantine camps. If an individual doesn't show any symptoms and tests negative after two weeks, he/she is permitted to leave such quarantine camps.
“We recommend that negative tests for COVID-19 should be required before patients are discharged from hospital,” Cao said.
The authors note that the interpretation of their findings might be limited by the study’s sample size. Moreover, the estimated duration of viral shedding was limited by the low frequency of respiratory specimen collection and a lack of measurable genetic material detection in samples.
According to co-author Zhibo Liu from Jinyintan Hospital, China: “Older age, showing signs of sepsis on admission, underlying diseases like high blood pressure and diabetes, and the prolonged use of non-invasive ventilation were key factors in the deaths of these patients.”
Poorer outcomes in older people may be due, in part, to the age-related weakening of the immune system and increased inflammation that could promote prolonged responses to inflammation, causing lasting damage to the heart, brain, and other organs.
For the first time, the study describes the complete picture of the disease progression. The median duration of fever was about 12 days in survivors, which was similar in non-survivors.
But the cough may last for a long time—45% of survivors still had a cough on discharge. In survivors, dyspnoea (shortness of breath) would cease after about 13 days, but would last until death in non-survivors.