Source: Centers for Disease Control and Prevention
Coronavirus Disease 2019 Basics
A novel coronavirus is a new coronavirus that has not been previously identified. The virus causing coronavirus disease 2019 (COVID-19), is not the same as the coronaviruses that commonly circulate among humans and cause mild illness, like the common cold.
A diagnosis with coronavirus 229E, NL63, OC43, or HKU1 is not the same as a COVID-19 (coronavirus) diagnosis. Patients with COVID-19 (coronavirus) will be evaluated and cared for differently than patients with common coronavirus diagnosis.
On February 11, 2020, the World Health Organization announced an official name for the disease that is causing the 2019 novel coronavirus outbreak, first identified in Wuhan China. The new name of this disease is coronavirus disease 2019, abbreviated as COVID-19. In COVID-19, ‘CO’ stands for ‘corona,’ ‘VI’ for ‘virus,’ and ‘D’ for disease. Formerly, this disease was referred to as “2019 novel coronavirus” or “2019-nCoV”.
There are many types of human coronaviruses, including some that commonly cause mild upper-respiratory tract illnesses. COVID-19 (coronavirus) is a new disease caused by a novel (or new) coronavirus that has not previously been seen in humans. The name of this disease was selected following the World Health Organization (WHO) best practice for the naming of new human infectious diseases.
How It Spreads
COVID-19 is caused by a coronavirus called SARS-CoV-2. Coronaviruses are a large family of viruses that are common in people and many different species of animals, including camels, cattle, cats, and bats. Rarely, animal coronaviruses can infect people and then spread between people. This occurred with MERS-CoV and SARS-CoV, and now with the virus that causes COVID-19. More information about the source and spread of COVID-19 is available on the Situation Summary: Source and Spread of the Virus.
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).
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 newly emerged coronaviruses.
The virus that causes COVID-19 is spreading from person-to-person. People are thought to be most contagious when they are symptomatic (the sickest). 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. More recently the virus has also been detected in asymptomatic persons.
How long someone is actively sick can vary so the decision on when to release someone from isolation is made using a test-based or non-test-based strategy (i.e. time since illness started and time since recovery) in consultation with state and local public health officials. The decision involves considering the specifics of each situation, including disease severity, illness signs and symptoms, and the results of laboratory testing for that patient.
Learn more about CDC’s guidance on when to release someone from isolation and discharge hospitalized patients with COVID-19. For information on when someone who has been sick with COVID-19 is able to stop home isolation see Interim Guidance for Discontinuation of In-Home Isolation for Patients with COVID-19.
Someone who has been released from isolation is not considered to pose a risk of infection to others.
Quarantine means separating a person or group of people who have been exposed to a contagious disease but have not developed illness (symptoms) from others who have not been exposed, in order to prevent the possible spread of that disease. Quarantine is usually established for the incubation period of the communicable disease, which is the span of time during which people have developed illness after exposure.
For COVID-19 (coronavirus), the period of quarantine is 14 days from the last date of exposure, because 14 days is the longest incubation period seen for similar coronaviruses. Someone who has been released from COVID-19 (coronavirus) quarantine is not considered a risk for spreading the virus to others because they have not developed illness during the incubation period.
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 (coronavirus) associated with food. Before preparing or eating food, it is important to always wash your hands with soap and water for 20 seconds for general food safety. Throughout the day, wash your hands after blowing your nose, coughing or sneezing, or going to the bathroom.
It may be possible that a person can get COVID-19 (coronavirus) 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.
In general, because of poor survivability of these coronaviruses on surfaces, there is likely very low risk of spread from food products or packaging that are shipped over a period of days or weeks at ambient, refrigerated, or frozen temperatures.
Learn what is known about the spread of COVID-19 (coronavirus).
It is not yet known whether weather and temperature impact the spread of COVID-19 (coronavirus). 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 (coronavirus) will decrease when the weather becomes warmer. There is much more to learn about the transmissibility, severity, and other features associated with COVID-19 (coronavirus) and investigations are ongoing.
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.
How to Protect Yourself
This is a rapidly evolving situation and the risk assessment may change daily. The latest updates are available on CDC’s Coronavirus Disease 2019 (COVID-19) website.
Visit the COVID-19 (coronavirus) Prevention and Treatment page to learn about how to protect yourself from respiratory illnesses, like COVID-19 (coronavirus).
There is information for people who have had close contact with a person confirmed to have, or being evaluated for, COVID-19 (coronavirus) available online.
Early information out of China, where COVID-19 (coronavirus) first started, shows that some people are at higher risk of getting very sick from this illness including older adults, and people who have serious chronic medical conditions like heart disease, diabetes, and lung disease.
If you are at higher risk of getting very sick from COVID-19 (coronavirus), you should: stock up on supplies; take everyday precautions to keep space between yourself and others; when you go out in public, keep away from others who are sick; limit close contact and wash your hands often; and avoid crowds, cruise travel, and non-essential travel. If there is an outbreak in your community, stay home as much as possible. Watch for symptoms and emergency signs. Watch for symptoms and emergency signs. If you get sick, stay home and call your doctor. More information on how to prepare, what to do if you get sick, and how communities and caregivers can support those at higher risk is available on People at Risk for Serious Illness from COVID-19 (coronavirus).
In light of new data about how COVID-19 spreads, along with evidence of widespread COVID-19 illness in communities across the country, CDC recommends that people wear a cloth face covering to cover their nose and mouth in the community setting.
This is an additional public health measure people should take to reduce the spread of COVID-19 in addition to (not instead of) social distancing, frequent hand cleaning and other everyday preventive actions. A cloth face covering is not intended to protect the wearer, but may prevent the spread of virus from the wearer to others. This would be especially important in the event that someone is infected but does not have symptoms.
A cloth face covering should be worn whenever people must go into public settings (grocery stores, for example). Medical masks and N-95 respirators are reserved for healthcare workers and other first responders, as recommended by current CDC guidance.
Symptoms and Testing
Current symptoms reported for patients with COVID-19 (coronavirus) have included mild to severe respiratory illness with fever1, cough, and difficulty breathing. Read about COVID-19 (coronavirus) Symptoms.
Not everyone needs to be tested for COVID-19. For information about testing, see Testing for COVID-19.
State and local health departments who have identified a person under investigation (PUI) should immediately notify CDC’s Emergency Operations Center (EOC) to report the PUI and determine whether testing for COVID-19 (coronavirus) at CDC is indicated. The EOC will assist local/state health departments to collect, store, and ship specimens appropriately to CDC, including during after hours or on weekends/holidays.
For more information on specimen collection, see CDC Information for Laboratories.
Using the CDC-developed diagnostic test, a negative result means that the virus that causes COVID-19 (coronavirus) was not found in the person’s sample. In the early stages of infection, it is possible the virus will not be detected.
For COVID-19 (coronavirus), a negative test result for a sample collected while a person has symptoms likely means that the COVID-19 (coronavirus) is not causing their current illness.
Health Care Professionals and Health Departments
For recommendations and guidance on persons under investigation; infection control, including personal protective equipment guidance; home care and isolation; and case investigation, see Information for Health Care Professionals. For information on specimen collection and shipment, see Information for Laboratories. For information for public health professional on COVID-19 (coronavirus), see Information for Public Health Professionals.