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Coronavirus (COVID-19): Understanding a Pandemic

Resources from the CDC on COVID-19

Update and Interim Guidance on Outbreak COVID-19 in Wuhan, China



The Centers for Disease Control and Prevention (CDC) continues to closely monitor and respond to the COVID-19 outbreak caused by the novel coronavirus, SARS-CoV-2.

This CDC Health Alert Network (HAN) Update highlights guidance and recommendations for evaluating and identifying patients who should be tested for COVID-19 that were shared on March 4, 2020, on the CDC COVID-19 website at It supersedes the guidance and recommendations provided in CDC’s HAN 428 distributed on February 28, 2020.

The outbreak that began in Wuhan, Hubei Province, has now spread throughout China and to 101 other countries and territories, including the United States. As of March 8, 2020, there were more than 105,000 cases reported globally. In addition to sustained transmission in China, there is now community spread in several additional countries. CDC has updated travel guidance to reflect this information (

As of March 7, 2020, there were a total of 213 cases within the United States, of which, 49 were among repatriated persons from high-risk settings. Among the other 164 cases that were diagnosed in the United States, 36 were among persons with a history of recent travel in China or other affected areas, and 18 were persons in close contact with another confirmed COVID-19 patient (i.e., person-to-person spread); 110 cases are currently under investigation. During the week of February 23, community spread of the virus that causes COVID-19 was reported in California in two places, Oregon, and Washington. Community spread in Washington resulted in the first reported case of COVID-19 in a healthcare worker, and the first outbreak in a long-term care facility. The first death due to COVID-19 was also reported from Washington; there have now been 11 reported deaths in the U.S. from COVID-19. As of March 7, 2020, COVID-19 cases had been reported by 19 states. CDC will continue to work with state and local health departments, clinicians, and laboratorians to identify and respond to other cases of COVID-19, especially those with an unknown source of infection, to limit further community spread. The most recent update describing COVID-19 in the United States can be found at

Recognizing persons who are at risk for COVID-19 is a critical component of identifying cases and preventing further transmission. With expanding spread of COVID-19, additional areas of geographic risk are being identified and the criteria for considering testing are being updated to reflect this spread. In addition, with increasing access to testing, the criteria for testing for COVID-19 have been expanded to include more symptomatic persons, even in the absence of travel history to affected areas or known exposure to another case, to quickly detect and respond to community spread of the virus in the United States.

2019 Novel Coronavirus

US map of affected areas

Situation Summary

The Centers for Disease Control and Prevention (CDC) is closely monitoring an outbreak of respiratory illness caused by a novel (new) coronavirus first identified in Wuhan, Hubei Province, China. Chinese authorities identified the new coronavirus, which has resulted in thousands of confirmed cases in China, including cases outside Wuhan City. Additional cases have been identified in a growing number of other international locations, including the United States. There are ongoing investigations to learn more.