Covid-19 crisis: Asymptomatic people can infect surfaces
Different surfaces in the hotel rooms of two students, who returned to China from studying abroad on March 19 and March 20, without symptoms were tested three hours after they tested positive on the second day in quarantine, according to the study.Updated: May 21, 2020 05:17 IST
In a finding that has major implications for people using public transport and sharing office space as the lockdown is relaxed in India, a study has found that asymptomatic and presymtomatic people with the coronavirus disease (Covid-19) are highly infectious and can extensively contaminate the environment in a very short time.
Different surfaces in the hotel rooms of two students, who returned to China from studying abroad on March 19 and March 20, without symptoms were tested three hours after they tested positive on the second day in quarantine, according to the study.
Eight of the 22 samples collected from the two rooms tested positive for Covid-19.These included door handles, light switches, faucets, thermometers, TV remotes, pillows, duvet covers, sheets, towels, bathroom door handles, toilet seats and flushing buttons, said the study, which was published in Emerging Infectious Diseases journal of the US Centers for Disease Control and Prevention.
“The detection of Sars-CoV-2 RNA (genetic material) in the surface samples of the sheet, duvet cover, and pillow cover highlights the importance of proper handling procedures when changing or laundering used linens of SARS-CoV-2 patients,” concluded researchers.
What has fuelled the spread of the Covid-19 pandemic is the long incubation period of the infection, which, on average, takes 5.1 days to show symptoms, according to a study published in March in The Annals of Internal Medicine. During this period, patients do not develop symptoms of cough, fever or difficulty in breathing but begin spreading the infection.
Some people have no symptoms because they have mild disease or because they are pre-symptomatic, but they can be highly infective. Young, healthy people are more likely to have mild or no symptoms compared to older people and those with chronic illnesses.
“Studies show infected people take on average five to six days to develop symptoms, but are infective from day one. Lockdowns prevent undiagnosed infected people from stepping out and infecting others, but with less restricted travel, chances of exposure increase, especially because it is a younger, healthier workforce that is the most mobile,” said Dr Ambarish Dutta, associate professor of epidemiology and public health, Indian Institute of Public Health, Bhubaneswar.
An earlier study published in the journal, Nature Medicine, on April 15 found around 44% infections were spread by people with no symptoms, with people with Covid-19 being the most infectious two or three days before the symptoms appear. Another study in March found 48% cases in Singapore and 62% in Tianjin, China, were spread by people with no symptoms.
The risk of infection and severe disease is higher in older people, men, the obese, the poor, those living in densely populated areas, and people with chronic kidney disease.
“As lockdown lifts and people become mobile, social distancing, wearing masks and hand washing will be the only defence against the coronavirus disease (Covid-19), for which there is no approved vaccine or cure,” said Dr Dutta.