“The CDC determined that the risk of surface transmission is low and secondary to the primary routes of transmission of the virus through direct contact droplets and aerosols,” said Vincent Hill, chief of the Division of Waterborne Disease Prevention, in a conference call sponsored by the CDC.
Hill said the risk of transmission from touching a surface, while small, is high indoors. Outdoors, the sun and other factors can destroy viruses, Hill said.
The virus dies “quickly” on porous surfaces, but can persist longer on hard interior surfaces.
The research also suggested that surface transmission was most likely in the first 24 hours after a person was infected, and that households where a person had Covid-19 had lower transmission rates when the household cleaned and disinfected surfaces.
“In most situations, cleaning surfaces with soap or detergent, and not disinfecting, is enough to reduce the already low risk of virus transmission through surfaces,” Hill said. “Generally, it is not necessary to disinfect surfaces, unless a sick or Covid-19 positive person has been in the house in the last 24 hours.”
Hill said cleaning should focus on high-touch areas, like doorknobs and light switches.
Household cleaners pose a hazard
People may be using household cleaning products to protect themselves from Covid-19, but misuse can have dangerous consequences, Hill added.
Frequent cleaning and disinfection of surfaces may have minimal impact on viral transmission and contribute to the “theater of hygiene,” he added.
“Putting on a show” to clean and disinfect “can be used to give people a sense of security that they are being protected from the virus, but this can be a false sense of security, if other prevention measures such as the use of masks, physical distancing, and hand hygiene are not done consistently, “Hill said.
“It could also make people feel less need to participate in these other important prevention measures.”
Additional data shows that disinfectants themselves can pose a risk.
“Public research indicates that some people may purposely drink, inhale or spray their skin with disinfectants, without understanding that using disinfectants in this way can cause serious harm to their bodies,” he said.
Hill cited CDC research from June 2020 showing that, of those surveyed, “only 58% knew that bleach should not be mixed with ammonia, because the bleach-ammonia mixture creates a toxic gas that damages the lungs. of people”.
And bleach itself can be harmful.
“Nineteen percent wash food products with bleach, which could lead to their consumption of bleach that is not washed, which can harm the body because bleach is toxic. Eighteen percent used household cleanser on bare skin, which it can damage the skin and cause rashes and burns, “Hill said.
Hill added that surveillance data shows that the volume of calls to poison centers in 2020 for disinfectants was higher than in 2018 or 2019.
Alternative methods of disinfection can also be time-wasting or even risky, the CDC says in the updated guide.
“The effectiveness of alternative methods of surface disinfection, such as ultrasonic waves, high-intensity ultraviolet radiation, and blue LED light against the virus that causes COVID-19 has not been fully established,” says the CDC on its website. updated.