The virus responsible for Covid-19 can remain infectious on surfaces such as banknotes, phone screens and stainless steel for 28 days, researchers say. The findings from Australia's national science agency suggest SARS-Cov-2 can survive for far longer than thought. However, the experiment was conducted in the dark. UV light has already been shown to kill the virus. Some experts have also thrown doubt on the actual threat posed by surface transmission in real life.