Spread and transmission
The virus that causes COVID-19 is thought to spread mainly from person to person, mainly through respiratory droplets produced when an infected person coughs or sneezes. These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs. Spread is more likely when people are in close contact with one another (within about 6 feet).
Some infections can be spread by exposure to the virus in small droplets and particles that can linger in the air for minutes to hours. These viruses may be able to infect people who are further than 6 feet away from the person who is infected or after that person has left the space.
This kind of spread is referred to as airborne transmission and is an important way that infections like tuberculosis, measles, and chicken pox are spread.
COVID-19 seems to be spreading easily and sustainably in the community (“community spread”) in many affected geographic areas. Community spread means people have been infected with the virus in an area, including some who are not sure how or where they became infected.
Learn what is known about the spread of COVID-19.
The virus that causes COVID-19 is spreading from person-to-person. Someone who is actively sick with COVID-19 can spread the illness to others. That is why CDC recommends that these patients be isolated either in the hospital or at home (depending on how sick they are) until they are better and no longer pose a risk of infecting others.
How long someone is actively sick can vary so the decision on when to release someone from isolation is made on a case-by-case basis in consultation with doctors, infection prevention and control experts, and public health officials and involves considering specifics of each situation including disease severity, illness signs and symptoms, and results of laboratory testing for that patient.
Current CDC guidance for when it is OK to release someone from isolation is made on a case by case basis and includes meeting all of the following requirements:
- The patient is free from fever without the use of fever-reducing medications.
- The patient is no longer showing symptoms, including cough.
- The patient has tested negative on at least two consecutive respiratory specimens collected at least 24 hours apart.
Someone who has been released from isolation is not considered to pose a risk of infection to others.
Community spread means people have been infected with the virus in an area, including some who are not sure how or where they became infected. Each health department determines community spread differently based on local conditions. For information on community spread in your area, please visit your health department’s website.
Community mitigation is a set of actions that people and communities can take to slow the spread of infectious diseases like COVID-19. The goal of community mitigation in areas with local COVID-19 transmission is to slow its spread and to protect all individuals, especially those at increased risk for severe illness, while minimizing the negative impacts of these strategies. For more information, see Community Mitigation Framework.
There are several actions that individuals and communities can take to help reduce the chance that they, their families and friends, and their communities get COVID-19. In general, the more cases spreading in your community, the more likely it will spread to you or your family. Also, the more people an individual interacts with, and the longer each interaction lasts, the higher the risk of viral spread. Location can be a factor, too, with outdoor activities generally being less risky than indoor activities.
Individuals can take the following community mitigation actions:
- Wear a mask (with some exceptions) when in public settings or around others not living in the same household
- Follow healthy hygiene practices, such as frequent hand washing
- Practice social distancing
- Stay home when sick
- Clean and disinfect frequently touched surfaces daily
Communities can take the following actions:
- Promote behaviors that prevent spread
- Maintain healthy environments
- Ensure institutions in the community are practicing appropriate precautions
- Prepare for when someone gets sick
- Close businesses and schools, and limit other services
If you have been around someone who was identified as a close contact to a person with COVID-19, closely monitor yourself for any symptoms of COVID-19. You do not need to self-quarantine unless you develop symptoms or if the person identified as a close contact develops COVID-19.
Yes. You should still self-quarantine for 14 days since your last exposure. It can take up to 14 days after exposure to the virus for a person to develop COVID-19 symptoms. A negative result before end of the 14-day quarantine period does not rule out possible infection. By self-quarantining for 14 days, you lower the chance of possibly exposing others to COVID-19.
People with COVID-19 can still spread the virus even if they don’t have any symptoms. If you were around someone who had COVID-19, it is critical that you stay home and away from others for 14 days from the last day that you were around that person. Staying home and away from others at all times helps your health department in the fight against COVID-19 and helps protect you, your family, and your community.
If you have been around someone who is sick with COVID-19, local authorities, the health department, or your doctor may recommend that you get tested for COVID-19. The health department may be able to provide resources for testing in your area.
- While you are waiting for your COVID-19 test result, stay home away from others (self-quarantine) and monitor your health for symptoms of COVID-19 to protect your friends, family, and others from possibly getting COVID-19.
- If your test is positive, you should continue to stay home and self-isolate away from others and monitor your health. If you have symptoms of COVID-19 and they worsen or become severe, you should seek emergency medical care. Severe symptoms include trouble breathing, persistent pain or pressure in the chest, confusion, inability to wake or stay awake, or bluish lips or face. Someone from the health department may call you to
- Check on your health
- Discuss who you have been around, and
- Ask where you have spent time while you may have been able to spread COVID-19 to others.
- If your test is negative and you don’t have symptoms, you should continue to stay home and self-quarantine away from others for 14 days after your last exposure to COVID-19 and follow all recommendations from the health department. This is important because symptoms can appear up to 14 days after you’ve been exposed and are infected. A negative result before the end of your quarantine period does not rule out possible infection. Additionally, you do not need a repeat test unless you develop symptoms, or if you require a test to return to work.
- If your test is negative and you have symptoms, you should continue to self-quarantine away from others for 14 days after your last exposure to COVID-19 and follow all recommendations from the health department. Additional medical consultation and a second test may be needed if your symptoms do not improve.
You can be around others after:
- 10 days since symptoms first appeared; and
- 24 hours with no fever without the use of fever-reducing medications; and
- COVID-19 symptoms have improved (for example, cough, shortness of breath).
Most people do not require testing to decide when they can be around others; however, if your healthcare provider recommends testing, they will let you know when you can resume being around others based on your test results.
Note that these recommendations do not apply to persons with severe COVID-19 or with severely weakened immune systems (immunocompromised). For more information, visit CDC’s guidelines.
If you have had close contact with an infected person, stay home for 14 days and maintain social distance (at least 6 feet) from others at all times.
- Self-monitor for symptoms.
- Check temperature twice a day.
- Watch for fever, cough, or shortness of breath, or other symptoms of COVID-19.
- Avoid contact with people at higher risk for severe illness from COVID-19.
- If symptoms develop, contact your health provider and follow CDC guidance.
For more information about how to protect yourself, see the CDC’s How to Protect Yourself & Others.
Contact tracing slows the spread of COVID-19 by
- Letting people know they may have been exposed to COVID-19 and should monitor their health for symptoms;
- Helping people who may have been exposed to COVID-19 get tested; and
- Asking people to self-isolate if they have COVID-19 or self-quarantine if they are in close contact with someone with COVID-19.
During contact tracing, the health department staff will not ask you for
- Social Security number
- Bank account information
- Salary information
- Credit card numbers
Learn more about contact tracing
If you are diagnosed with COVID-19, someone from the health department may call you to check on your health, discuss who you have been around, and ask where you spent time while you may have been able to spread COVID-19 to others. You will also be asked to continue to stay at home and self-isolate, away from others.
- Your name will not be shared with those you came in contact with.
- The health department staff will not ask you for
- Social Security number
- Bank account information
- Salary information, or
- Credit card numbers
- Self-isolation means staying at home in a specific room away from other people and pets, and using a separate bathroom, if possible.
- Self-isolation helps slow the spread of COVID-19 and can help protect the health of your family, friends, neighbors, and others you may come in contact.
- If you need support or assistance while in self-isolation, your health department or community organizations may be able to provide assistance.
Watch for or monitor your symptoms of COVID-19. If your symptoms worsen or become severe, you should seek medical care.
For COVID-19, a close contact is anyone who was within 6 feet of an infected person for at least 15 minutes. An infected person can spread COVID-19 starting 48 hours (or 2 days) before the person had any symptoms or tested positive for COVID-19.
Yes, you are still considered a close contact even if you were wearing a mask while you were around someone with COVID-19. Masks are meant to protect other people in case you are infected, and not to protect you from becoming infected.
Yes, if you agree to participate in contact tracing for COVID-19 with the health department, your information is secure.
Discussions with health department staff are confidential. This means that your personal and medical information will be kept private and only shared with those who may need to know, like your healthcare provider. Your name will not be shared with those you came in contact with. If you have been diagnosed with COVID-19, the health department will only notify people you were in close contact with (within 6 feet for more than 15 minutes) that they might have been exposed to COVID-19.
Health departments may use case management tools to help make the contact tracing process more efficient. If you choose to provide information through one of these tools, your information is secure and stored with the health department. These tools also help health departments quickly receive and analyze information about COVID-19. Case management tools are under the same laws and regulations for all sensitive health information use (e.g. HIPPA). You must provide consent for the health department to collect information using a case management tool. Just like traditional contact tracing, digital tools will not collect information regarding money, Social Security numbers, bank account information, salary information, or credit card numbers.
Exposure notification tools may be an app that you can download on your personal cell phone. If you choose to download an exposure notification app for COVID-19, your information is secure. Exposure notification apps are developed in collaboration with or endorsed by health departments. These apps undergo rigorous testing to determine their trustworthiness, security, and ability to protect people’s privacy. Until you give consent to share information with your local health department, any information you have entered into the app is stored only on your personal phone. Your information is stored only on your own phone and is not sent to the health department or any other third party. The app and your information can be deleted any time. When you consent to share your information with the local health department, your information is secure.
Discussions with health department staff are confidential. This means that your personal and medical information will be kept private and only shared with those who may need to know, like your health care provider.
If you have been diagnosed with COVID-19, your name will not be shared with those you came in contact with. The health department will only notify people you were in close contact with (within 6 feet for more than 15 minutes) that they might have been exposed to COVID-19. Each state and jurisdiction use their own method for collecting and protecting health information. To learn more, contact your state or local health department.
You may also be interested in: If I participate contact tracing for COVID-19 using a digital tool, is my personal health information secure?.
No, you are not required to download an app to give information for contact tracing for COVID-19. Health departments commonly use case management tools to make the contact tracing process more efficient. These types of tools are not downloaded on personal cell phones.
If you choose to give information to your local or state health department for contact tracing for COVID-19, you do not need to download an app on your cell phone. The health department staff may call you to
- Check on your health,
- Discuss who you have been around, and
- Ask where you have spent time while you may have been able to spread COVID-19 to others.
It is up to you to decide if you download an exposure notification app for COVID-19.
No, there will not be a national app for contact tracing. There are many options available now, and it is up to each state and individual to decide which tools best fit their needs.
Here are some ways to protect yourself: Don’t pay a contact tracer, give out your Social Security number or financial information, share your immigration status, or click on links or download anything sent from a contact tracer.
It may be possible that people can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes, but this isn’t thought to be the main way the virus spreads. CDC recommends cleaning and disinfection of frequently touched surfaces and frequent handwashing or the use of hand sanitizer with at least 60% alcohol as best practice measures for prevention of COVID-19 and other viral respiratory illnesses.
Some cleaning and disinfection products are not recommended for use on car seats and booster seats. Owners should follow the manufacturer’s cleaning instructions for their car seats and booster seats. Motor vehicle crashes are a leading cause of death for children in the United States. Always buckle children in age- and size-appropriate car seats, booster seats, and seat belts when riding in a vehicle.
There is still a lot that is unknown about COVID-19 and how it spreads. Coronaviruses are thought to be spread most often by respiratory droplets. Although the virus can survive for a short period on some surfaces, it is unlikely to be spread from domestic or international mail, products or packaging. However, it may be possible that people can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes, but this is not thought to be the main way the virus spreads.
Learn more about safe handling of deliveries and mail.
At this time, CDC has no data to suggest that this new coronavirus or other similar coronaviruses are spread by mosquitoes or ticks. The main way that COVID-19 spreads is from person to person. See how coronavirus spreads for more information.
In general, respiratory viruses are not known to be transmitted by blood transfusion, and there have been no reported cases of transfusion-transmitted coronavirus.
Coronaviruses are generally thought to be spread from person to person through respiratory droplets. Currently, there is no evidence to support transmission of COVID-19 associated with food. Before preparing or eating food it is important to always wash your hands with soap and water for at least 20 seconds for general food safety. Throughout the day use a tissue to cover your coughing or sneezing, and wash your hands after blowing your nose, coughing or sneezing, or going to the bathroom.
It is not yet known whether weather and temperature impact the spread of COVID-19. Some other viruses, like the common cold and flu, spread more during cold weather months but that does not mean it is impossible to become sick with these viruses during other months. At this time, it is not known whether the spread of COVID-19 will decrease when weather becomes warmer. There is much more to learn about the transmissibility, severity, and other features associated with COVID-19 and investigations are ongoing.
The virus that causes COVID-19 has been found in untreated wastewater. Researchers do not know whether this virus can cause disease if a person is exposed to untreated wastewater or sewerage systems. There is no evidence to date that this has occurred. At this time, the risk of transmission of the virus that causes COVID-19 through properly designed and maintained sewerage systems is thought to be low.
Sometimes floodwater can mix with wastewater. CDC is not aware of any scientific reports of the virus being spread by swallowing or coming in contact with water contaminated by feces from an infected person. Stay out of floodwater to avoid hazards and illnesses from contaminants that are not associated with COVID-19. To learn more about COVID-19 and wastewater, see question, “Can the COVID-19 virus spread through sewerage systems?”
The virus that causes COVID-19 has not been detected in drinking water. Conventional water treatment methods that use filtration and disinfection, such as those in most municipal drinking water systems, should remove or inactivate the virus that causes COVID-19.
There is no evidence that the virus that causes COVID-19 can be spread to people through the water in pools, hot tubs, spas, or water play areas. Proper operation and maintenance (including disinfection with chlorine and bromine) of these facilities should inactivate the virus in the water.
While there is ongoing community spread of the virus that causes COVID-19, it is important for individuals as well as owners and operators of these facilities to take steps to ensure health and safety:
- Everyone should follow local and state guidance that may determine when and how recreational water facilities may operate.
- Individuals should continue to protect themselves and others at recreational water venues both in and out of the water—for example, by practicing social distancing and good hand hygiene.
- In addition to ensuring water safety and quality, owners and operators of community pools, hot tubs, spas, and water play areas should follow the interim guidance for businesses and employers for cleaning and disinfecting their community facilities.
CDC is not aware of any scientific reports of the virus that causes COVID-19 spreading to people through the water in lakes, oceans, rivers, or other natural bodies of water.
The virus mainly spreads when respiratory droplets from infected people land in the mouths or noses of others or possibly when inhaled into the lungs by others. If a public beach or other swim area in a natural body of water is open, it is important for all visitors and staff to take steps to slow the spread of the virus:
- Stay home if you are infected or might be infected with the virus that causes COVID-19.
- Stay at least 6 feet apart (in and out of the water) from people you don’t live with.
- Wear cloth masks when not in water.
- Cover coughs and sneezes with a tissue (or use the inside of your elbow), throw used tissues in the trash, and wash hands.
- Wash your hands often with soap and water for at least 20 seconds. Use hand sanitizer with at least 60% alcohol if soap and water are not readily available.
See Considerations for Public Beaches for more information.
RNA of the virus that causes COVID-19 has been found in untreated wastewater, which can come from combined sewer overflows (rainwater runoff, domestic sewage, and industrial wastewater) and other (such as, leaking septic tanks or animal waste from farms nearby) and enter swim areas. While data are limited, there is little evidence of infectious virus in wastewater. Plus, CDC is not aware of any scientific reports of the virus being spread by swallowing or coming in contact with water contaminated by feces (poop) from an infected person.
At lakes, oceans, and rivers with routine water quality monitoring programs, staff look for changes in fecal (poop) contamination of the water. Water quality advisories and beach closures alert the public to avoid getting in or on the water because of increased fecal contamination. Learn more about healthy swimming in natural bodies of water and access water quality information by state.
CDC is not aware of any scientific reports of the virus that causes COVID-19 spreading to people through the water in pools, including saltwater pools. Plus, proper operation of public pools (such as at an apartment complex or owned by a community) and disinfection of the water (with chlorine or bromine) should inactivate the virus. Saltwater pools are chlorinated pools.
In traditional pools, chlorine products (such as granules or liquid bleach) are added to the water to disinfect it. In saltwater pools, table salt (made up of sodium and chloride) is added to the water, and an electrical current is then run through the water with dissolved salt. This creates the same disinfecting form of chlorine that is created when chlorine products are added to the water in traditional pools.
In most cases, it is safe to wash your hands with soap and tap water during a Boil Water Advisory. Follow the guidance from your local public health officials. If soap and water are not available, use an alcohol-based hand sanitizer containing at least 60% alcohol.
The virus that causes COVID-19 has been found in the feces of some patients diagnosed with COVID-19. However, it is unclear whether the virus found in feces may be capable of causing COVID-19. There has not been any confirmed report of the virus spreading from feces to a person. Scientists also do not know how much risk there is that the virus could be spread from the feces of an infected person to another person. However, they think this risk is low based on data from previous outbreaks of diseases caused by related coronaviruses, such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).
- CDC: Guidance for reducing health risks to workers handling human waste or sewage
- CDC: Healthcare professionals: Frequently asked questions and answers
- CDC: Healthy Water
- Occupational Safety and Health Administration: COVID-19 Control and Prevention: Solid waste and wastewater management workers and employers
- World Health Organization: Water, sanitation, hygiene and waste management for COVID-19
At this time, there is no evidence that companion animals, including pets, can spread COVID-19 to people or that they might be a source of infection in the United States. To date, CDC has not received any reports of pets becoming sick with COVID-19 in the United States.
Pets have other types of coronaviruses that can make them sick, like canine and feline coronaviruses. These other coronaviruses cannot infect people and are not related to the current COVID-19 outbreak.
However, since animals can spread other diseases to people, it’s always a good idea to practice healthy habits around pets and other animals, such as washing your hands and maintaining good hygiene. For more information on the many benefits of pet ownership, as well as staying safe and healthy around animals including pets, livestock, and wildlife, visit CDC’s Healthy Pets, Healthy People website.
You should restrict contact with pets and other animals while you are sick with COVID-19, just like you would around other people. Although there have not been reports of pets becoming sick with COVID-19 in the United States, it is still recommended that people sick with COVID-19 limit contact with animals until more information is known about the new coronavirus. When possible, have another member of your household care for your animals while you are sick. If you are sick with COVID-19, avoid contact with your pet, including petting, snuggling, being kissed or licked, and sharing food or bedding. If you must care for your pet or be around animals while you are sick, wash your hands before and after you interact with pets and wear a mask.
Imported animals will need to meet CDC and USDA requirements for entering the United States. At this time, there is no evidence that companion animals, including pets and service animals, can spread COVID-19. As with any animal introduced to a new environment, animals recently imported should be observed daily for signs of illness. If an animal becomes ill, the animal should be examined by a veterinarian. Call your local veterinary clinic before bringing the animal into the clinic and let them know that the animal was recently imported from another country.
This is a rapidly evolving situation and information will be updated as it becomes available.
Other coronaviruses have been found in North American bats in the past, but there is currently no evidence that the virus that causes COVID-19 is present in any free-living wildlife in the United States, including bats. In general, coronaviruses do not cause illness or death in bats, but we don’t yet know if this new coronavirus would make North American species of bats sick. Bats are an important part of natural ecosystems, and their populations are already declining in the United States. Bat populations could be further threatened by the disease itself or by harm inflicted on bats resulting from a misconception that bats are spreading COVID-19. However, there is no evidence that bats in the United States are a source of the virus that causes COVID-19 for people. Further studies are needed to understand if and how bats could be affected by COVID-19.
Currently, there is no evidence to suggest the virus that causes COVID-19 is circulating in free-living wildlife in the United States, or that wildlife might be a source of infection for people in the United States. The first case of a wild animal testing positive for the virus in the United States was a tiger with a respiratory illness at a zoo in New York City. However, this tiger was in a captive zoo environment ,and public health officials believe the tiger became sick after being exposed to a zoo employee who was infected and spreading the virus.
If a wild animal were to become infected with the virus, we don’t know whether the infection could then spread among wildlife or if it could spread to other animals, including pets. Further studies are needed to understand if and how different animals, including wildlife, could be affected by COVID-19. Because wildlife can carry other diseases, even without looking sick, it is always important to enjoy wildlife from a distance.
Take steps to prevent getting sick from wildlife in the United States:
- Keep your family, including pets, a safe distance away from wildlife.
- Do not feed wildlife or touch wildlife droppings.
- Always wash your hands and supervise children washing their hands after working or playing outside.
- Leave orphaned animals alone. Often, the parents are close by and will return for their young.
- Consult your state wildlife agency’s guidance if you are preparing or consuming legally harvested game meat.
- Do not approach or touch a sick or dead animal – contact your state wildlife agency instead.
The virus that causes COVID-19 is thought to spread from close contact (i.e., within about 6 feet) with a person who is infected with the virus. The virus spreads primarily through respiratory droplets produced when an infected person coughs, sneezes, or talks.
This type of spread is not a concern after death. It may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes, but this is not thought to be the main way the virus spreads. If the deceased person had confirmed or suspected COVID-19, avoid kissing, washing, or shrouding the body before, during, and after the body has been prepared, if possible. For more information on recommended precautions while handling the belongings and the body of someone who died from COVID-19, see Funeral Guidance.
CDC does not recommend the use of sanitizing tunnels. There is no evidence that they are effective in reducing the spread of COVID-19. Chemicals used in sanitizing tunnels could cause skin, eye, or respiratory irritation or damage.
CDC does not recommend disinfection of sidewalks or roads. Spraying disinfectant on sidewalks and roads is not an efficient use of disinfectant supplies and has not been proven to reduce the risk of COVID-19 to the public. The risk of spreading the virus that causes COVID-19 from these surfaces is very low and disinfection is not effective on these surfaces..