'The surface issue has essentially gone away': Experts revise thinking on coronavirus transmission

An employee prepares to clean the display while preparing to restock paper products while shopping on Stanford Shop Rite on March 14, 2020.

According to the Centers for Disease Control and Prevention, although the coronavirus is most commonly spread through respiratory droplets in close contact and from contaminated surfaces to people, health officials encourage the cleaning and disinfection of frequently touched objects and surfaces because This virus will remain on a variety of materials for hours to days.

A worker wipes fares at the Montgomery Street Bay Area Rapid Transit (BART) station in San Francisco, California on March 7, 2020. As the coronavirus continues to spread, people are taking preventive measures to protect themselves and the general public by cleaning surfaces and wearing protective masks.

A worker from Kenya Railway sprayed disinfectant on the inner surface of the station on March 18, 2020 to prevent the spread of the COVID-19 coronavirus at the Central Railway Station in Nairobi, Kenya. -The Kenyan government confirmed that there have been new positive cases of COVID-19 coronavirus in Kenya. On March 18, 2020, the total number of official cases in East African countries reached 7. African countries have become one of the last countries to hit the global COVID-19 coronavirus epidemic, but with the increase in cases, many countries are now taking strict measures to stop the deadly disease. (LUIS TATO / AFP Photography) (LUIS TATO / AFP Photography: Getty Images)

An employee of Stadtwerke Gruppe Halle/Saale cleans and disinfects the buses of Hallesche Verkehrs AG, a public transportation tool in Halle/Saale, Germany on Monday, March 16, 2020. All scheduled vehicles of local transportation companies have been thoroughly cleaned and disinfected. every day. This applies especially to contact surfaces such as armrests, handles, steering wheels and ticket machines. For most people, the new coronavirus will only cause mild or moderate symptoms, such as fever and cough. For some people, especially the elderly and people with health problems, it can cause more serious diseases, including pneumonia. . (Hendrik Schmidt / dpa via AP)

TOPSHOT-On March 17, 2020, at Wat Suthat Thepwararam (Wat Suthat Thepwararam) monastery in Bangkok, volunteers cleaned the surface due to concerns about the spread of the COVID-19 novel coronavirus. )

We know that when an infected person coughs, sneezes, speaks, sings, or even breathes, the coronavirus will spread through human-to-human contact.

However, some early laboratory studies have shown that COVID-19 can be obtained through contact with infected particles that can survive on the surface for days or weeks. This has led people to vigorously wipe light switches, scrub groceries and tribal cleaning supplies.

As researchers become more aware of the virus that causes COVID-19, SARS-CoV-2, scientists are less concerned about the spread of so-called poisonous gas.

Monica Gandhi, an infectious disease doctor and researcher at UCSF, said: "The superficial problems have basically disappeared." "The virus is spread mainly through massive shedding from the nose and mouth."

In other words, touching a surface or object with a lot of virus particles, and then touching your nose, mouth or eyes, may be a slight risk of infection. But the main route of transmission is inhalation of respiratory droplets and aerosols, which can

It took a few hours.

Below are answers to frequently asked questions about how the coronavirus spreads on the surface and in the air. As we learn more, we will update this article.

Although spreading the virus from contact with contaminated surfaces is considered low risk, health experts recommend wearing a mask and maintaining regular hygiene to prevent yourself from contracting the virus without contact with objects.

According to laboratory research, this is the epitome of how long the coronavirus can survive on the surface under laboratory conditions.

And medical journal

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(Foil, window frame, ladder, etc.): 2-8 hours

(Mail, tissues, toilet paper, magazines, newspapers, etc.): 3 hours

(Coins, jewelry, wires, etc.): 4 hours

(Transport box, food packaging, etc.): 24 hours

(Bags, bedding, blankets, carpets, hair bands, etc.): 2 days

(Furniture, table top, etc.): 4 days

(Light switches, credit cards, food packaging, ATM buttons, etc.): 3-7 days

(Tableware, keys, pots and pans, door handles, etc.)

5 days

(Glass, goblet, window, mirror, etc.): 5 days

: 4 days

(External): 7 days

There is not enough clear evidence to show the behavior of the virus under realistic conditions, such as exposure to direct sunlight, extreme heat or cold conditions.

The role of aerosols in causing the spread of the indoor virus COVID-19 is

Proposed by the World Health Organization in July, and supported by evidence presented by 239 researchers in 32 countries.

According to the virus, the virus can stay in the air for up to three hours.

. Based on the aerosol produced by breathing or speaking, it can also move at least 13 feet-twice the established physical distance criterion.

According to a study conducted by experimenters under experimental conditions, talking can release thousands of droplets per second, and these droplets can be suspended in the air for 8 to 14 minutes.

Prevent or at least limit your exposure to these infectious virus droplets and aerosol particles.

Experts also recommend cleaning the environment in indoor environments through ventilation and filtration.

"When you are indoors, please consider changing your breath," he said

Professor of Medicine and Infectious Diseases, University of California, San Francisco. Ensure good ventilation. This is all related to reducing risk. "

According to the CDC, a person may get the coronavirus by touching an object or object with the virus on the surface and then touching their mouth, nose or eyes. But this is not considered the main route of infection.

After touching the surface touched by other people, please clean your hands with alcohol-based hand sanitizer or wash them thoroughly with soap and water for 20 seconds. The organization added that no matter whether cold or hot water is used, there is no effect because "temperature does not seem to affect the removal of microorganisms."

Avoid touching your face with unwashed hands.

Practice using soap and water to routinely clean frequently touched surfaces, including tables, door handles, light switches, countertops, handles, desks, phones, keyboards, toilets, faucets, sinks, etc.

The United States has a list of the most effective anti-coronavirus cleaning products.

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Commercial products that are effective against pathogens are also listed.

According to the Centers for Disease Control and Prevention, food or packaging that is shipped for days or weeks at room temperature, refrigerated or frozen temperature has little risk of transmission.

There is no evidence that the coronavirus is spread through food.

As a general precaution, all products should be soaked in warm water before eating, including the vegetables and fruits you peel (such as bananas). Avoid using chemicals such as bleach or alcohol directly on the food you want to eat, but discard or disinfect any packaging, especially the areas most likely to be handled by others.

Always wash your hands before preparing or eating food. In addition, after bringing it into the packaging bag, or after traveling to a grocery store or other places that may touch the infected surface, wash your hands with soap and water for 20 seconds.

Yes. There is no evidence that the virus can be spread through imported goods because its surface viability is weak over time.

No need to sterilize the packaging. If possible, open them and dispose of the packaging outside your home. Also, disinfect your hands after handling them.

Yes. A sample taken from the soles of the feet of medical staff working in the intensive care unit of a hospital in Wuhan, China, tested positive for coronavirus on the soles of their shoes.

The research report released by the Centers for Disease Control and Prevention stated: "Therefore, the soles of medical personnel may act as carriers."

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Outside the hospital, the CDC does not provide advice on handling footwear. When entering your home, please consider leaving your shoes at the door, minimize contact with your shoes, and ensure that you wash your hands thoroughly and disinfect any surfaces that you touch after touching them.

If your shoes are machine washable, please follow the laundry guidelines below for disinfection.

To clean electronic devices, such as phones, tablets, remote controls, and keyboards, CDC recommends following the manufacturer's disinfection instructions. If there is no instruction, please use an alcohol cloth or spray with at least 70% alcohol content and dry the surface thoroughly.

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If someone in your family has COVID-19, please take the following measures:

• Enclose the area used by the patient.

• Wear disposable gloves to clean and disinfect the surface.

• Clean the surface with soap and water.

• Use one of the following methods for disinfection: diluted household bleach solution (if applicable to the surface); alcohol solution containing at least 70% alcohol; household cleaners and disinfectants. Never mix household bleach with ammonia or any other cleaning agents.

• For soft surfaces (for example, carpeted floors, carpets and curtains), please use soap and water or detergent for cleaning.

The CDC recommends wearing disposable gloves when handling clothes, towels, sheets, and other items in suspected infected areas. Don't shake dirty clothes. Before handling, please use the warmest appropriate water setting and dry the items. The dirty clothes of the sick can be washed with other people's items.

Clean and disinfect the laundry basket according to the surface guidelines listed above.

Wash hands thoroughly after handling dirty clothes.

Aidin Vaziri is a writer for the San Francisco Chronicle. e-mail:

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Aidin Vaziri reports on news, health and entertainment in the San Francisco Chronicle. Since 2004, Beyond has been working for newspapers, he has worked for "Rolling Stone", "National Geographic", MTV and E! Entertainment venues, etc.