Coronaviruses are a large group of viruses that cause diseases in animals and humans. They often circulate among animals and can sometimes evolve and infect people. In humans, the viruses can cause mild respiratory infections, like the common cold, but can lead to serious illnesses, like pneumonia.
The 2019 novel coronavirus (COVID-19, previously known as 2019-nCoV) emerged in a seafood and poultry market in Wuhan, China in December 2019. It likely spread from an unknown animal to humans. Human-to-human transmission occurs through close contact.
What are the symptoms? How can you tell the difference between the novel coronavirus and a cold or influenza (flu)?
The symptoms are similar, including fever, cough, and shortness of breath. Some patients with novel coronavirus have had gastrointestinal problems or diarrhea. For most people in the US, a fever or cough is usually caused by a cold or flu. Those in the US are not at risk from novel coronavirus unless they have recently visited China or have had close contact with someone who has a confirmed case of coronavirus.
There have been very few confirmed cases of novel coronavirus in the US, compared to at least 19 million illnesses, 180,000 hospitalizations, and 10,000 deaths from flu during the 2019-2020 season. The flu poses a much larger threat for most people in the US.
Are people contagious before they develop symptoms?
There is evidence that the novel coronavirus can be spread before an individual develops symptoms. This poses a problem because people who do not know they are infected may continue to go to work, school, and other public places. People who are sick and have symptoms are more likely to stay home, which means fewer opportunities for the virus to spread from one person to another. When asymptomatic transmission occurs, infection control experts and public health officials may need to take additional measures, such as isolating patients or using quarantines.
How dangerous is novel coronavirus?
Whenever a new virus emerges, it is hard to predict how dangerous the disease will be. Cases may go unrecognized or under-reported. Most cases of the novel coronavirus have been in China, where diagnostic tests and other resources have been scarce. As more cases are confirmed, scientists and public health officials can develop a clearer picture of the full spectrum of disease, including who is at greatest risk for severe complications and who is more likely to have a milder illness.
Information about the novel coronavirus is changing rapidly.
What should people do if they think they may have been infected?
Individuals who have been to China in the past two weeks or have had close contact with someone who has a confirmed case of coronavirus should call a healthcare professional if they have any of the symptoms.
It is important to call first, so that the clinic or hospital can prepare and prevent the spread of infection. To diagnose a potential case, healthcare professionals will run tests to rule out flu and other common infections.
What can individuals do to protect themselves?
Healthy habits can help prevent the spread of coronavirus and other respiratory viruses:
- Wash hands often with soap and water for at least 20 seconds
- Avoid touching your eyes, nose, and mouth
- Avoid close contact with people who are sick
- Stay home when you are sick
- Cover your coughs and sneezes
- Clean and disinfect common objects and surfaces
There is currently no vaccine to prevent COVID-19 infection, but there are vaccines available to help prevent flu. Annual flu vaccination is recommended in the US for everyone age 6 months and older.
Do face masks or surgical masks protect against novel coronavirus?
CDC does not currently recommend the use of face masks among the general public.
Surgical masks are typically worn by healthcare professionals to prevent them from spreading germs to their patients. Surgical masks do not prevent the person who is wearing them from inhaling respiratory viruses. Spaces and gaps can form around the cheeks and edges of the mouth, making it easy for air and germs to move in and out. Proper handwashing is more effective in preventing respiratory infections.
Healthcare professionals sometimes wear N-95 respirators, a type of face mask that must be specially fitted. When worn properly, N-95 respirators can make breathing difficult, and they should not be worn for a long period of time.
Will warmer weather mean fewer cases of novel coronavirus?
COVID-19 is a new virus in humans, so it is too early to predict whether it will become seasonal. If it behaves like other respiratory viruses, including flu, it could abate as the weather gets warmer and become part of the usual cold and flu season. But scientists do not yet have enough information to know for certain. That’s why ongoing research to develop vaccines and antiviral drugs that are effective against coronaviruses is so important.
Should people avoid products shipped from China?
The virus likely would not survive such a trip. Coronaviruses may be transmitted by touching a surface, but they are more likely to be transmitted through the air. People can protect themselves through proper handwashing.
Why did public health authorities declare an emergency, and what does that mean?
US Health Secretary Alex M. Azar II declared a public health emergency on January 31, 2020 to help public health officials across the country respond to the novel coronavirus. In making this announcement, Secretary Azar noted that the risk to people in the US “remains low at this time, and we are working to keep this risk low.”
The emergency declaration gives state and local health departments more flexibility to shift staff and resources to coronavirus response activities. CDC continues to work closely with state health departments on disease surveillance, contact tracing, and providing interim guidance for clinicians on identifying and treating coronavirus infections.
Will the coronavirus become a pandemic, and what does that mean?
The World Health Organization (WHO) is responsible for designating a pandemic. Scientists use the term “pandemic” to describe a new virus that emerges and spreads to multiple countries throughout the world. It means that the new virus is widespread and is spreading efficiently in those countries, but it does not tell us how severe the virus may be.
Learn the most current information about 2019 novel coronavirus (COVID-19, previously known as 2019-nCoV) including outbreak locations, risk assessment, and travel guidance