The Centers for Disease Control and Prevention is responding to an outbreak of respiratory disease caused by a novel — meaning new — coronavirus that was first detected in China. It has now been detected in more than 100 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 Jan. 30, the International Health Regulations Emergency Committee of the World Health Organization declared the outbreak a “public health emergency of international concern.” On January 31, Health and Human Services Secretary Alex Azar II declared a public health emergency for the United States to aid the nation’s healthcare community in responding to COVID-19. On March 11, the WHO publicly characterized COVID-19 as a pandemic. On March 13, the President of the United States declared the COVID-19 outbreak a national emergency.
Source and spread of 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, named SARS-CoV-2.
The SARS-CoV-2 virus is a betacoronavirus, like MERS-CoV and SARS-CoV. All three 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.
Early on, many of the patients at the epicenter of the outbreak in Wuhan, Hubei Province, China, had some link to a large seafood and live animal market, suggesting animal-to-person spread.
Later, a growing number of patients reportedly did not have exposure to animal markets, indicating person-to-person spread. Person-to-person spread was subsequently reported outside Hubei and in countries outside China, including in the United States. Some international destinations now have ongoing community spread with the virus that causes COVID-19, as do some parts of the United States. Community spread means some people have been infected and it is not known how or where they became exposed.
The complete clinical picture with regard to COVID-19 is not fully known. Reported illnesses have ranged from very mild — including some with no reported symptoms — 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 percent of cases. Older people and people of all ages with severe chronic medical conditions — like heart disease, lung disease and diabetes — seem to be at higher risk of developing serious COVID-19 illness.
Status as a pandemic
A pandemic is a global outbreak of disease. Pandemics happen when a new virus emerges to infect people and can spread between people sustainably. Because there is little to no pre-existing immunity against the new virus, it spreads worldwide.
The virus that causes COVID-19 is infecting people and spreading easily from person-to-person. Cases have been detected in most countries worldwide and community spread is being detected in a growing number of countries.
This is the first pandemic known to be caused by the emergence of a new coronavirus. In the past century, there have been four pandemics caused by the emergence of novel influenza viruses. As a result, most research and guidance around pandemics is specific to influenza, but the same premises can be applied to the current COVID-19 pandemic.
Pandemics begin with an investigation phase, followed by recognition, initiation and acceleration phases. The peak of illnesses occurs at the end of the acceleration phase, which is followed by a deceleration phase, during which there is a decrease in illnesses. Different countries can be in different phases of the pandemic at any point in time and different parts of the same country can also be in different phases of a pandemic.
Who’s at risk of exposure?
The immediate risk of being exposed to this virus is still low for most Americans, but as the outbreak expands, that risk will increase. Healthcare workers caring for patients with COVID-19, and close contacts of those people, are at elevated risk of exposure.
Travelers returning from affected locations where community spread is occurring are at elevated risk of exposure, with level of risk dependent on where they traveled.
Who’s at risk of severe illness?
Early information out of China shows that some people are at higher risk of getting very sick from this illness, including senior citizens and people who have pre-existing serious, chronic medical conditions.
There are ongoing investigations to learn more about this virus. This is a rapidly evolving situation, and the CDC will provide more information as it becomes available.
(Editor’s note: This information was provided by the CDC and has been abridged. Read more at https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/summary.html. In the coming weeks, the GUIDON will continue to relay information from the CDC and other agencies regarding COVID-19.)