Source: CDC.gov, www.cdc.gov/covid19.

The Centers for Disease Control and Prevention (CDC) has confirmed an infection with the virus that causes COVID-19 [coronavirus] in California in a person who reportedly did not have relevant travel history or exposure to another known patient with COVID-19.

At this time, the patient’s exposure is unknown. It’s possible this could be an instance of community spread of COVID-19, which would be the first time this has happened in the United States. Community spread means spread of an illness for which the source of infection is unknown. It’s also possible, however, that the patient may have been exposed to a returned traveler who was infected.

This case was detected through the U.S. public health system — picked up by astute clinicians. This brings the total number of COVID-19 cases in the United States to 15.

The federal government has been working closely with state, local, tribal, and territorial partners, as well as public health partners, to respond to this public health threat. Unprecedented, aggressive efforts have been taken to contain the spread and mitigate the impact of this virus.

This is a rapidly evolving situation. CDC will continue to update the public as circumstances warrant.  For more information about COVID-19 visit www.cdc.gov/covid19.

Background

CDC is responding to an outbreak of respiratory disease caused by a novel (new) coronavirus that was first detected in Wuhan City, Hubei Province, China and which has now been detected in 37 locations internationally, including cases 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 concernexternal icon” (PHEIC). On January 31, 2020, Health and Human Services Secretary Alex M. Azar II declared a public health emergency (PHE) for the United States to aid the nation’s healthcare community in responding to COVID-19.

Source and Spread of the Virus

Coronaviruses are a large family of viruses that are common in 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 in the COVID-19 outbreak in Wuhan, 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 has been reported outside China, including in the United States and other locations. Chinese officials report that sustained person-to-person spread in the community is occurring in China. In addition, other destinations have apparent community spread, meaning some people have been infected who are not sure how or where they became infected. Learn what is known about the spread of newly emerged coronaviruses.

Source and Spread of the Virus

Coronaviruses are a large family of viruses that are common in 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 in the COVID-19 outbreak in Wuhan, 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 has been reported outside China, including in the United States and other locations. Chinese officials report that sustained person-to-person spread in the community is occurring in China. In addition, other destinations have apparent community spread, meaning some people have been infected who are not sure how or where they became infected. Learn what is known about the spread of newly emerged coronaviruses.

Situation in U.S.

Imported cases of COVID-19 in travelers have been detected in the U.S. Person-to-person spread of COVID-19 also has been seen among close contacts of returned travelers from Wuhan.

SCN Editorial note: Today marks the first time this virus has spread in the community in the United States.

Illness Severity

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. Learn more about the symptoms associated with COVID-19.

There are ongoing investigations to learn more. This is a rapidly evolving situation and information will be updated as it becomes available.

Risk Assessment

Outbreaks of novel virus infections among people are always of public health concern. The risk from these outbreaks depends on characteristics of the virus, including how well it spreads between people, the severity of resulting illness, and the medical or other measures available to control the impact of the virus (for example, vaccine or treatment medications). The fact that this disease has caused illness, including illness resulting in death, and sustained person-to-person spread is concerning. These factors meet two of the criteria of a pandemic. As community spread is detected in more and more countries, the world moves closer toward meeting the third criteria, worldwide spread of the new virus.

The potential public health threat posed by COVID-19 is high, both globally and to the United States.

But individual risk is dependent on exposure.

• For the general American public, who are unlikely to be exposed to this virus at this time, the immediate health risk from COVID-19 is considered low.
• Under current circumstances, certain people will have an increased risk of infection, for example healthcare workers caring for patients with COVID-19 and other close contacts of persons with COVID-19. CDC has developed guidance to help in the risk assessment and management of people with potential exposures to COVID-19.

However, it’s important to note that current global circumstances suggest it is likely that this virus will cause a pandemic. In that case, the risk assessment would be different.

What May Happen

More cases are likely to be identified in the coming days, including more cases in the United States. It’s also likely that person-to-person spread will continue to occur, including in the United States. Widespread transmission of COVID-19 in the United States would translate into large numbers of people needing medical care at the same time. Schools, childcare centers, workplaces, and other places for mass gatherings may experience more absenteeism. Public health and healthcare systems may become overloaded, with elevated rates of hospitalizations and deaths. Other critical infrastructure, such as law enforcement, emergency medical services, and transportation industry may also be affected. Health care providers and hospitals may be overwhelmed. At this time, there is no vaccine to protect against COVID-19 and no medications approved to treat it. Nonpharmaceutical interventions would be the most important response strategy.

For more information or to subscribe to free CDC updates, go to www.cdc.gov/