CDC on Wednesday confirmed the first case of the new coronavirus in the United States among a patient who wasn't exposed to anyone who had either traveled to other countries affected by the virus or who had a suspected or confirmed case of the virus.

The news came as President Trump announced Vice President Pence will be in charge of the country's coronavirus response.

Background: CDC says US should prepare for more coronavirus cases

Reports of the new coronavirus first surfaced in early December 2019 in Wuhan, China. According to the World Health Organization (WHO), the main symptoms of the virus are fever and lesions in both lungs. Some patients also have reported difficulty breathing, WHO said.

As of Thursday, officials reported more than 82,400 cases of the virus globally, with most of those cases occurring in mainland China. Officials said as of Thursday there had been more than 2,804 deaths linked to the virus, and all but 60 of the deaths occurred in mainland China.

The number of newly reported cases in China has started to slow, but the number of newly reported cases in other countries has surged over the past week. For instance, experts noted that Iran, which had reported no cases of the virus at the start of last week, reported 245 cases and 26 deaths from the virus as of Thursday. Italy also has seen a large spike in cases, growing from no cases to more than 453 cases and 13 deaths in less than a week.

In the United States, CDC early Wednesday reported a total of 59 confirmed cases of the virus. CDC at the time said 45 cases involved Americans who contracted the virus elsewhere and then repatriated to the United States, 12 cases involved patients who had traveled to China and were diagnosed after they returned to the United States, and two cases involved patients who contracted the virus via human-to-human transmission in the United States from patients who had traveled to China.

CDC confirms local coronavirus case

Later on Wednesday, CDC announced that it had confirmed a new case of coronavirus among a patient who resides in Solano County, California, that "may be the first case of community spread in the United States," the New York Times reports. Travis Air Force Base, where hundreds of Americans who repatriated to the United States from China and Americans who were on the Diamond Princess cruise ship have been quarantined, is located in Solano County. According to the Washington Post, many of the individuals who were under quarantine at the base have been released, but so far there is no known connection between those individuals and the latest case.

CDC said the patient does not appear to have been exposed to anyone who had traveled to other countries affected by the new coronavirus or anyone who had a suspected or confirmed case of the virus. "At this time, the patient's exposure is unknown," CDC said, adding, "The case was detected through the U.S. public health system—picked up by astute clinicians."

However, CDC noted, "It's also possible … that the patient may have been exposed to a returned traveler who was infected."

Officials at the University of California's Davis Medical Center (UC Davis) in an email sent to employees late Wednesday wrote that the patient had been admitted to the hospital on Feb. 19. According to the officials, the patient had been transferred to UC Davis from another in hospital in Northern California. At the time, the patient had a suspected viral infection and was on a ventilator.

The UC Davis officials wrote that providers at the medical center immediately asked CDC to test the patient for the virus, but CDC did not administer the test until Feb. 23. According to the officials, CDC waited about four days to administer the test because the patient at the time did not fit the agency's criteria for testing patients for the virus. Currently, CDC restricts testing to individuals who have traveled to China or who know have had contact with an individual who had a confirmed case of the virus.

The hospital officials noted in the email that the patient is not the first coronavirus case UC Davis has treated, "and because of the precautions we have had in place since this patient's arrival, we believe there has been minimal potential for exposure here at UC Davis Medical Center."

California's Department of Public Health also said it already has begun tracing people who might have come in contact with the new patient.

Experts say case highlights need for additional screening

Jennifer Nuzzo, an epidemiologist and senior scholar at the Johns Hopkins Center for Health Security, said it would be concerning if CDC does verify that the new case is community spread because "it would confirm what we have long suspected—that there is a good chance there already are people infected in this country and that the virus is circulating undetected." She said, "It points to the need for expanded surveillance so we know how many more are out there and how to respond."

William Schaffner, an infectious disease specialist at Vanderbilt University, said providers in Solano County may want to start testing broader sets of patients to see whether there are unidentified individuals who are infected with the coronavirus. "Physicians are going to want to start testing everybody with a fever and a cough. They're going to want to do that and the patients are going to want to do that," he said.

However, providers' ability to test patients for the new coronavirus is limited, as some diagnostic tests distributed to local governments by CDC were flawed. At this time, only CDC and officials in 12 states are able to test patients for the virus, and CDC must perform all confirmatory tests, the Times reports.

Trump says Pence will lead US coronavirus response

CDC announced the new case shortly after Trump announced that Pence will lead the United States' response to the coronavirus—though Trump stopped short of naming Pence as the country's coronavirus czar.

Trump also tried to subdue fears about the coronavirus' spread in the United States, saying public health containment measures and travel and entry restrictions have so far stopped the new coronavirus from becoming widespread in the country. "The risk to the American people remains very low," Trump said.

Still, Trump added that his administration is preparing for potential worst-case scenarios, Politico reports. "We're very, very ready for this," he said, adding, "We have the greatest experts, really in the world, right here."

But some observers raised concerns that Trump's comments seemed misaligned with earlier warnings from CDC officials that U.S. providers, businesses, and schools should start preparing for the possibility that the new coronavirus could become widespread in the United States and "upend Americans' daily lives," the Post reports.

To that end, Tom Inglesby, an infectious diseases physician and director of the Johns Hopkins Center for Health Security, said, "It's really important for the U.S. government to be speaking with one common voice about these issues right now." He continued, "It will erode confidence in the effort if one part of the government says something in the beginning of the day, and another part of the government says something contradictory at the end of the day" (Caryn Rabin, New York Times, 2/27; Neergaard/Alonso-Zaldivar, Associated Press, 2/27; Lai et al., New York Times, 2/27; CDC website, 2/26; CDC release, 2/26; Caryn Rabin/Fink, New York Times, 2/27; Bernstein et al., Washington Post, 2/27; Karlamangla/Cosgrove, Los Angeles Times, 2/27; Colliver, Politico, 2/26; Olorunnipa et al., Washington Post, 2/26; Cook/McGraw, Politico, 2/26; Thielking, STAT News, 2/26).