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Background Information

The CDC is responding to an outbreak of respiratory disease caused by a new coronavirus that was first detected in China and has now been detected in more than 70 locations internationally, including in the United States. The virus has been named “SARS-CoV-2” and the disease it causes has been named “Coronavirus Disease 2019” (abbreviated “COVID-19”).

On January 30, 2020, the International Health Regulations Emergency Committee of the World Health Organization declared the outbreak a “public health emergency of international concern.” On January 31, 2020, Health and Human Services Secretary Alex M. Azar II declared a public health emergency for the United States to aid the nation’s health care community in responding to COVID-19.

On March 11, the WHO declared COVID-19 a pandemic as the number of infected countries grows. Read more here.

Source and Spread of the Virus

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, such as with MERS-CoV, SARS-CoV, and now with this new virus, SARS-CoV-2.

The SARS-CoV-2 virus is a betacoronavirus, like MERS-CoV and SARS-CoV. All 3 of these viruses have their origins in bats. The sequences from U.S. patients are similar to the one that China initially posted, suggesting a likely single, recent emergence of this virus from an animal reservoir.

Both MERS-CoV and SARS-CoV have been known to cause severe illness in people. The complete clinical picture with regard to COVID-19 is not fully understood. Reported illnesses have ranged from mild to severe, including illness resulting in death. While information so far suggests that most COVID-19 illness is mild, a report out of China suggests serious illness occurs in 16% of cases. Older people and people with compromised immune systems and certain underlying health conditions - such as heart disease, lung disease and diabetes, to name a few - seem to be at greater risk of serious illness.

Learn more about the symptoms associated with COVID-19.

Risk Assessment

The potential public health threat posed by COVID-19 is very high, to the United States and globally. At this time, however, most people in the United States will have little immediate risk of exposure to this virus. This virus is NOT currently spreading widely in the United States. However, it is important to note that current global circumstances suggest it is likely that this virus will cause a pandemic.

Current risk assessment:

  • For most of the American public, who are unlikely to be exposed to this virus at this time, the immediate health risk from COVID-19 is considered low.
  • People in communities where ongoing community spread with the virus that causes COVID-19 has been reported are at elevated, though still relatively low risk of exposure.
  • Health care workers caring for patients with COVID-19 are at elevated risk of exposure.
  • Close contacts of persons with COVID-19 also are at elevated risk of exposure.
  • Travelers returning from affected international locations where community spread is occurring also are at elevated risk of exposure.

CDC has developed guidance to help in the risk assessment and management of people with potential exposures to COVID-19.