The Centers for Disease Control and Prevention (CDC) and other federal, state, and local departments and agencies are taking aggressive measures to slow the transmission of the outbreak of acute respiratory illness caused by a novel coronavirus (2019-nCoV) in the United States, including rapid and accurate identification of cases and managing individuals traveling from China to the United States, according to an early release published in the Morbidity and Mortality Weekly Report.1

A cluster of cases of this acute respiratory illness was first reported by Chinese health officials on December 31, 2019, in the city of Wuhan, Hubei Province, and by January 7, 2020, officials confirmed that the 2019-nCoV was responsible for this initial cluster.1 By February 4, 2020, the National Health Commission of China had confirmed 20,471 cases, including 2788 (13.6%) severe cases and 425 fatalities (2.1%). As of that same date, there were 11 reported cases in the United States.1 Because of this rapid increase in the number of people affected by the virus, on February 11, 2020, the World Health Organization (WHO), officially named the constellation of symptoms resulting from infection with 2019-nCoV, COVID-19.2

According to a Situation Report released by the WHO on February 20, 2020, the current number of cases of confirmed COVID-19 infection are 75,748 globally, 74,675 of which are in China.3

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The World Health Organization director general declared the 2019-nCoV outbreak to be a Public Health Emergency of International Concern on January 30, 2020. On January 31, 2020, the United States Department of Health and Human Services secretary made a similar declaration, and the president of the United States signed a Proclamation on Suspension of Entry as Immigrants and Nonimmigrants of Persons who Pose a Risk of Transmitting 2019 Novel Coronavirus, thus limiting entry into the United States from persons who traveled to mainland China to only US citizens or permanent residents and their families.

Aggressive measures taken by the CDC and other organizations to slow 2019-nCoV transmission require the identification of cases and their contacts in the United States, and appropriate assessment and care of individuals traveling from mainland China to the United States. Although the measures taken may not prevent an eventual widespread outbreak, they will slow the spread of illness, giving healthcare providers and the public time to better prepare to combat the illness should widespread transmission and substantial 2019-nCoV illness occur. In addition, the measures will afford the opportunity to better characterize the virus to appropriately guide public health recommendations and medical response, including diagnosis, treatment, and vaccines. Further, the World Health Organization has cited an update to modeling estimates for COVID-19 infection: new research places a new estimate for the infection-fatality ratio of 0.94% (95% CI, 0.37-2.9), replacing replaces the lowest estimate of 0.33%, but remaining below the highest estimate of 1.0%.3

The 11 confirmed cases of 2019-nCoV were diagnosed in the following states: Arizona (1), California (6), Illinois (2), Massachusetts (1), and Washington (1). Two cases were close contacts of 2 confirmed 2019-nCoV cases and were diagnosed as part of routine monitoring of case contacts. All patients are being monitored closely for illness progression. No deaths have been reported in the United States.

Some coronaviruses have been the result of human-animal interactions, such as severe acute respiratory syndrome (SARS) and middle-east respiratory syndrome (MERS), and preliminary 2019-nCoV investigations also suggest a zoonotic origin. Although it is evident the virus can spread person-to-person via respiratory droplets, the ease of transmission is not year clear. Signs and symptoms of infection with 2019-nCoV include cough, fever, and shortness of breath, and the incubation period of illness most likely occurs within 2 to 14 days following infection. Although older adults and individuals with compromised immune systems or underlying health conditions may be at higher risk for severe illness from 2019-nCoV, many characteristics of the new coronavirus and its affect on vulnerable subgroups in the population is not yet clear.

Criteria suggested to guide evaluation and testing for suspected cases of 2019-nCoV include: fever or signs or symptoms of lower respiratory tract illness in any person who has had close contact with a patient with laboratory-confirmed 2019-nCoV infection within 14 days of symptom onset; fever and signs or symptoms of lower respiratory tract illness in any person with a history of travel from Hubei Province, China, within 14 days of symptom onset; or fever and signs or symptoms of lower respiratory tract illness requiring hospitalization in any person with a history of travel from mainland China within 14 days of symptom onset. 

On January 17, 2020, CDC Quarantine staff members instituted enhanced screening of travelers on direct and connecting flights from Wuhan, China, arriving at 3 major international airports in the United States: Los Angeles (LAX), New York City (JFK), and San Francisco (SFO), which then expanded to include those arriving in Atlanta (ATL) and Chicago (ORD). These 5 airports receive approximately 85% of all air travelers to the United States from Wuhan, China. The United States Customs and Border Protection officials identify travelers arriving from Wuhan and refer them to the CDC for medical screening. As of February 1, a total of 3099 individuals on 437 flights have been screened, 5 individuals have been referred to local health care providers, and 1 person tested positive for 2019-nCoV.

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Within one week of the Chinese health officials posting the full 2019-nCoV genomic sequence on January 10, 2020, the CDC developed a Clinical Laboratory Improvement Amendments-approved real-time polymerase chain reaction to diagnose 2019-nCoV respiratory samples from clinical specimens, and on January 24, the CDC publicly posted the assay protocol for this test. In addition, the genome of the virus has been uploaded to GenBank, the National Institutes of Health genetic sequence database, and the CDC is growing the virus in cell culture to be used in further studies, including additional genetic characterization. Once the virus has been isolated, it will be made available through BEI Resources to assist further research.

Study investigators concluded, “2019-nCoV symptoms are similar to those of influenza (e.g., fever, cough, or sore throat), and the outbreak is occurring during a time of year when respiratory illnesses…are highly prevalent. To prevent influenza, all persons aged ≥6 months should receive an annual influenza vaccine.…Reducing the number of persons in the United States with seasonal influenza will reduce possible confusion with 2019-nCoV infection and possible additional risk to patients with seasonal influenza. Public health authorities are monitoring the situation closely.”


1. Patel A, Jernigan DB; 2019-nCoV CDC Response Team. Initial public health response and interim clinical guidance for the 2019 novel coronavirus outbreak — United States, December 31, 2019-February 4, 2020. MMWR Morb Mortal Wkly Rep. 2020;69(5):140-146.

2. Centers for Disease Control and Prevention. Coronavirus disease 2019 (COVID-19) situation summary. Updated February 23, 2020. Accessed February 24, 2020.

3. World Health Organization. Coronavirus disease 2019 (COVID-19) situation seport – 31. Updated February 20, 2020. Accessed February 24, 2020.

This article originally appeared on Infectious Disease Advisor