How Does Coronavirus Spread?

With cases of the new coronavirus reported in all 50 states, health officials are focused on slowing the spread. By understanding how coronavirus spreads, you can take the right steps so you don't get sick and infect others.

Person-to-Person Transmission

Experts believe the virus that causes COVID-19 spreads mainly from person to person. There are several ways this can happen:

  • Droplets or aerosols. When an infected person coughs, sneezes, or talks, droplets or tiny particles called aerosols carry the virus into the air from their nose or mouth. Anyone who is within 6 feet of that person can breathe it into their lungs.
  • Airborne transmission. Research shows that the virus can live in the air for up to 3 hours. It can get into your lungs if someone who has it breathes out and you breathe that air in.
  • Surface transmission. Another way to catch the new coronavirus is when you touch surfaces that someone who has the virus has coughed or sneezed on. You may touch a countertop or doorknob that's contaminated and then touch your nose, mouth, or eyes. The virus can live on surfaces like plastic and stainless steel for 2 to 3 days. To stop it, clean and disinfect all counters, knobs, and other surfaces you and your family touch several times a day.
  • Fecal-oral. Studies also suggest that virus particles can be found in infected people's poop. But experts aren't sure whether the infection can spread through contact with an infected person's stool. If that person uses the bathroom and doesn't wash their hands, they could infect things and people that they touch.

The virus most often spreads through people who have symptoms. But it is possible to pass it on without showing any signs. Some people who don't know they've been infected can give it to others. This is called asymptomatic spread. You can also pass it on before you notice any signs of infection, called presymptomatic spread.

Community Spread

Sometimes, a person can trace how they got the virus because they know that they've been in contact with someone who's sick. In other cases, the cause is unknown. Community spread is when someone gets the virus without any known contact with a sick person.

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Pets and COVID-19

A few pets have tested positive for the new coronavirus. Not all of these animals had signs of illness, but some have had mild symptoms. The animals may have caught the virus from close contact with humans who were infected.

Public health officials say they are still studying COVID-19 but that there’s no evidence that pets play a role in its spread.

How Easy Is It to Get Infected?

Researchers say that on average, every person who has COVID-19 will pass it on to 2 or 2.5 others. One study says that number is even higher, with one sick person infecting between 4.7 and 6.6 others.

By comparison, someone who has the flu will probably give it to an average of 1.1 to 2.3 others. But one person with measles might spread it to 12 to 18 others.

Can I Get Infected From Delivery Food, Packages, or Groceries?

It's highly unlikely that you'll catch COVID-19 from packages, groceries, or food. The important thing is to limit your contact with other people. If you do your own shopping, try to keep at least 6 feet away from others in the store. That might not be possible all the time, so wear a face mask, too. If you use a delivery service, have them leave groceries, food, or packages outside your front door if you can.

Wash your hands for at least 20 seconds before and after bringing things into your home. If you want, you can wipe down plastic, metal, or glass packaging with soap and water. Then clean and disinfect countertops and anything else you or your bags have touched.

Flattening the Curve

You may have seen a graph called "flattening the curve." It shows a tall, narrow curve and a short, wide curve. Through the graph is a line that shows how many sick people hospitals in a certain area can treat at one time. The tall curve goes above the line. That means too many people are sick at once: That region won't have enough hospital beds for all the people who will need treatment. The flatter curve shows what happens if the spread of the virus slows down. The same number of people may get sick, but the infections happen over a longer time, so hospitals can treat more people.

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How to Protect Yourself

The best way to slow the spread of the virus is to limit your contact with other people. This will help flatten the curve. There are a few ways to do this:

  • Work from home if you can.
  • Avoid travel when possible. This is especially important if you or someone you live with is older or has a health condition that raises the chances of serious COVID-19 illness.
  • Visit with family and friends by phone and computer instead of in person.
  • If you must go out, stand at least 6 feet away from people.
  • Follow local and state government recommendations or mandates on wearing face masks when you go out.
  • Wash your hands often.
  • If you’re sick, stay in a separate bedroom away from others in your home.
  • Do your shopping, especially for groceries or drugstore items, online if possible.
  • Keep your pets away from people and animals outside your home. Cats should stay indoors as much as possible.
  • Clean up pet waste properly. Wash your hands afterward and after you touch them, their food, or their toys.
  • If you have COVID-19 symptoms, limit contact with your pet. If you can’t have someone else take care of your animals, wear a face mask when you’re around them, and wash your hands before and after you interact with them.

It may seem extreme to limit large gatherings, ask people to work from home, and close schools, restaurants, and theaters. But health experts say these are the best ways to slow the spread of the virus. As some places ease these rules, keep in mind that the virus hasn’t gone away. Be careful about your contact with others.

When to Quarantine or Isolate

To stop the spread of coronavirus, people who are sick need to self-quarantine, or stay away from those who are well. Because you may not show symptoms right away, you should also self-quarantine if you know that you've come into contact with someone who has COVID-19.

  • Stay at home.
  • Don't have visitors.
  • Wash your hands often with soap and warm water.
  • Don't share personal items like dishes, utensils, and towels.
  • Clean frequently touched surfaces like counters, doorknobs, phones, and remote controls.

If you've tested positive for COVID-19, isolate yourself. Stay at home in a room that's separate from everyone else, if possible. Avoid contact with other people and pets. Wear a face mask when you have to be near other people.

If your symptoms get worse, call your doctor or hospital before you go in. Follow their instructions to get medical help.

Isolate yourself until there's no chance that you could spread the virus. Your doctor can tell you when it's safe to stop.

WebMD Medical Reference Reviewed by Brunilda Nazario, MD on August 05, 2020

Sources

SOURCES:

UpToDate: “Coronavirus disease 2019 (COVID-19).”

World Health Organization: “Coronavirus disease 2019 (COVID-19) Situation Report – 73,” “Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19).”

Pathogens: “SARS-CoV-2 and Coronavirus Disease 2019: What We Know So Far.”

Hartford HealthCare: “How to Avoid COVID-19 at the Supermarket.”

CDC: "Cases in U.S.," "How it Spreads," "Preventing the Spread of Coronavirus Disease 2019 in Homes and Residential Communities," “Recommendation Regarding the Use of Cloth Face Coverings, Especially in Areas of Significant Community-Based Transmission,” “Coronavirus and Travel in the United States,” “If You Have Animals.”

News release, CDC.

World Organisation for Animal Health: “Questions and Answers on the 2019 Coronavirus Disease (COVID-19).”

Columbia Mailman School of Public Health: "Public Health Rallies to 'Flatten the Curve.'"

Harvard Medical School: "Coronavirus Resource Center."

Johns Hopkins Medicine: "Coronavirus, Social Distancing and Self Quarantine."

Kaiser Health News: "Flattening the Curve and Social Distancing: Understanding the Drastic Measures That Experts Keep Talking About."

Michigan Health: "Flattening the Curve for COVID-19: What Does It Mean and How Can You Help?"

News release, National Institutes of Health.

Wisconsin Public Radio: “Social Distancing In Wisconsin: Your Questions, Answered.”

New England Journal of Medicine: “Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1.”

China CDC Weekly: “Notes from the Field: Isolation of 2019-nCoV from a Stool Specimen of a Laboratory-Confirmed Case of the Coronavirus Disease 2019 (COVID-19).”

MedRxiv: “The Novel Coronavirus, 2019-nCoV, is Highly Contagious and More Infectious Than Initially Estimated.”

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