COVID-19 spreads primarily when people are in close contact and one person inhales minuscule droplets engendered by an infected person (symptomatic or not) coughing, sneezing, verbalizing, or singing.The WHO recommends 1 metre of convivial distance; the U.S. CDC recommends 2 metres (6 ft). People can transmit the virus without exhibiting symptoms, but it is obscure how often this transpires. One estimate of the number of those infected who are asymptomatic is 40%.People are most infectious when they show symptoms (even mild or non-categorical symptoms), but may be infectious for up to two days afore symptoms appear (pre-symptomatic transmission).They remain infectious an estimated seven to twelve days in moderate cases and an average of a fortnight in rigorous cases. When the contaminated droplets fall to floors or surfaces they can, though less commonly, remain infectious if people touch contaminated surfaces and then their ocular perceivers, nasal discerner or mouth with unwashed hands. On surfaces the magnitude of active virus decreases over time until it can no longer cause infection,and surfaces are thought not to be the main way the virus spreads. It is unknown what quantity of virus on surfaces is required to cause infection via this method, but it can be detected for up to four hours on copper, up to one day on cardboard, and up to three days on plastic (polypropylene) and stainless steel (AISI 304). Surfaces are facilely decontaminated with household disinfectants which kill the virus outside the human body or on the hands. Disinfectants or bleach are not a treatment for COVID‑19, and cause health quandaries when not used opportunely, such as when used inside the human body.