A new study, published in The Lancet, describes the risk factors associated with Covid-19. Consistent with previous work on the subject, the team of Chinese scientists identified hypertension, diabetes and cardiovascular disease as aggravating factors. They have also studied the excretion of the virus over time. In the most severe cases, the patient produces infectious virions for a median duration of 20 days.
When the virus has finished replicating within its host cell, it moves out to infect others. Infectious virions can then be excreted from the body through preferred routes, such as the respiratory tract. Patients are contagious and can spread the virus to others. In the case of Covid-19, the timing of virus excretion, which is still unclear, was studied, among other data, in a study published in The Lancet.
The patient cohort consisted of 191 patients managed in two hospitals, Jiniyntan Hospital and Wuhan Pulmonary Hospital. They all had a severe form of Covid-19 disease requiring constant follow-up. At the time of the study, 137 survived and 54 died.
Surviving patients shed Sars CoV-2 virions for a median duration of 20 days after the onset of the disease. Data ranged from 8 days for the lowest duration of excretion to 37 days for the highest. Deceased patients were contagious until death.