The World Health Organization’s online information about coronavirus includes answers to questions about preventing its spread.

Following is the agency’s advice regarding what methods can and cannot kill the virus or otherwise prevent the transmission of COVID-19.

Hand-washing: Frequent washing with soap and water is effective in killing the virus. The water does not need to be hot, though warm water improves the soap’s efficiency. Dry hands thoroughly with a towel, paper towel or hand dryer.

Hand sanitizers: As an alternative to soap and water, a sanitizer with at least 60 percent alcohol can be used. Most commonly available sanitizers have at least that much alcohol.

Hand dryers: Hot-air dryers by themselves do not kill the virus.

Ultraviolet disinfection lamp: WHO discourages their use because of the potential for skin irritation.

Saline nose rinse: There is no evidence it fends off coronavirus infection, or any respiratory infection.

Spraying alcohol or chlorine on one’s body: This will not kill viruses that have entered the body, and it can harm mucous membranes. Alcohol (75 percent solution) and bleach- or chlorine-based disinfectants are appropriate for cleaning surfaces, if used according to instructions.

Garlic: No effect on coronavirus.

Sesame oil on the body: No effect on coronavirus.

Herbal remedies: No effect on coronavirus.

Smoking: No effect on coronavirus.

Vaccines: Flu or pneumonia vaccines have no effect on the coronavirus.

Antibiotics: They work only against bacteria, not any virus.

Masks: Wear a mask if you are coughing or sneezing. A healthy person needs to wear a mask only if taking care of a person with suspected coronavirus infection. Follow proper procedure in putting on, removing and disposing of the masks, including washing hands with soap and water before and after wearing a mask and not touching the front of a mask. Multiple masks are not more effective than one properly adjusted mask.