Based on what is currently known about COVID-19 and similar illnesses such as SARS and MERS, person-to-person transmission is the most likely source of infection, most frequently through respiratory droplets passed from talking, coughing or sneezing within about 6 feet.

Transmission by contaminated surfaces has not been documented, but there's evidence that the new coronavirus may remain viable for hours or days on surfaces.

In general, the federal Centers for Disease Control and Prevention recommends cleaning visibly dirty and frequently touched surfaces, followed by disinfection, as a best practice for the prevention of COVID-19 and other viral respiratory illnesses. The CDC released these guidelines to help households prepare for the possible spread of the coronavirus.

• Clean surfaces and objects that are touched frequently, including remotes, refrigerator and faucet handles, desks, doorknobs, railings, computer keyboards, light switches, phones and toys.

• Use soap and water to remove viruses and bacteria. Why? Cleaning safely removes germs, dirt and impurities from surfaces. Cleaning does not kill germs, but by removing them, it lowers their numbers and the risk of spreading various types of infections.

• Chemical disinfectants can kill germs on surfaces, but you can't skip the cleaning step. Those chemicals by themselves won't necessarily clean dirty surfaces or remove germs, but by killing germs on a surface after cleaning, disinfecting can further lower the risk of spreading infection.

• To disinfect with bleach, mix ⅓ cup of bleach per gallon of cold water or 4 teaspoons bleach per quart of cold water. Always mix bleach with cold water for disinfecting; hot water renders bleach ineffective. Bleach can degrade over time, so don't stockpile it.

• To ensure that the bleach-and-water mixture you use is effective, mix it the day you'll use it. Protect it from sunlight. Only apply to clean surfaces, as organic materials inactivate bleach.

• Never mix bleach with ammonia or other household cleaners. Doing so can produce a dangerous gas that even in small amounts can irritate the eyes, skin and respiratory tract.

• Never leave disinfectants where children or pets can access them.

• To disinfect with alcohol, use solutions with at least 70% alcohol, preferably ethyl alcohol. Since alcohol is flammable, limit its use as a surface disinfectant to small surface areas and use it in well ventilated spaces only.

• If you choose other disinfectants, use those with labels that say "EPA approved" for killing bacteria and viruses on solid surfaces. Always follow directions on product labels, especially instructions on how long to leave the product in place.

• Chemical disinfectants can make you sick if not used properly. Follow label instructions for precautions that you should take when applying, including wearing gloves and making sure you have good ventilation (such as opening windows) while using the product.

For additional tips on what to do if a family member is sick — such as how to handle dishes and laundry — go to cdc.gov/coronavirus/2019-ncov/community/home/cleaning-disinfection.