BEIJING : Scientists have assessed respiratory samples from 35 COVID-19 patients, and found that contagious coronavirus was "rarely detectable" beyond eight days after onset of illness, an advance that can help develop better self-isolation and quarantining protocols to curb the spread of the pandemic.The study, published in the journal Emerging Infectious Diseases, analysed 68 respiratory specimens from 35 COVID-19 patients in Hong Kong, of whom 32 had mild disease, and found that the novel coronavirus SARS-CoV-2 was rarely detectable beyond eight days after onset of illness.However, the researchers, including Ranawaka Perera from the University of Hong Kong, said the virus genetic material RNA was detectable for many weeks using the.