The first Covid-19 death in the United States was announced Saturday by Washington state health officials. In a Saturday press conference, President Donald Trump said the death occurred “overnight,” and that the person who died was a woman in her 50s. Robert Redfield, director of the Centers for Disease Control and Prevention (CDC), said Sunday evening the person who died was “erroneously identified the patient as a female.”

During the press conference, Redfield added that the person who died had not traveled recently. Officials with the Washington state Department of Health declined to give Vox any further details about the death.

The death comes following a Friday report of four new Covid-19 — the disease caused by the novel coronavirus known as SARS-CoV-2 — cases in three US states: one in Oregon, one in California and two in Washington.

The news of the death comes on the same day South Korean officials reported the biggest daily jump in infections in the country since the virus was first discovered six weeks ago and the day after the World Health Organization raised its Covid-19 risk assessment worldwide to the highest level.

While all previous US cases could be traced back to overseas travel or contact with someone already diagnosed with the virus, the origins of three of recently-reported cases are unknown. This has led medical experts to raise concerns that Covid-19 might be spreading within the US.

“If we were worried yesterday, we are even more worried today,” William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center, told the New York Times. “Now we have to ask: How widely, really widely, is this virus out there?”

An official in the Seattle area said the city may soon recommend people avoid areas and events where they would be in close contact with other people, such as parties, sporting events, and concerts.

There are 15 confirmed cases of the novel coronavirus in the US to date according to the CDC, not including 44 US citizens who were aboard the Diamond Princess cruise ship near Japan, the three citizens who were repatriated from Wuhan, China, and these four latest cases, which have been verified locally, but not yet by the CDC.

Coronavirus cases in South Korea jump to 3,150 — marking biggest daily jump in weeks

As US health officials work to respond to the reports of new cases, South Korean officials announced more than 800 new cases of Covid-19 Saturday, bringing the total number of confirmed cases in the country to 3,150.

The new cases mark the biggest daily jump in infections in the country. The first South Korean novel coronavirus case was just discovered six weeks ago, and since that time, it has already suffered 17 deaths due to the virus. South Korean officials are calling the increase a “critical moment” in the virus’s spread, and have warned people to practice “social distancing” for the next few days.

“We have asked you to refrain from taking part in public events, including a religious gathering or protest, this weekend,” vice health minister Kim Kang-lip told reporters Saturday. “Please stay at home and refrain from going outside and minimize contact with other people.”

In North Korea, leader Kim Jong-un also ordered a campaign to stop the spread of coronavirus Saturday. Officials there called the move “preemptive,” as no cases have yet been reported in the totalitarian country, but it is possible that the secretive regime is hiding an outbreak. North Korea has already closed its border with Russia and with China, where the virus first emerged in December.

Earlier this week, South Korean officials increased its virus threat level to the highest point since 2009. Doing so gave the government a legal basis to restrict public transportation and flights, limit tourism, and close both schools and cities, though officials have not yet made moves to do so.

More than 650 of the cases in South Korea are from Daegu, a southern city that’s home to a controversial church at the center of the outbreak. Many of the city’s cases have been connected to followers of the Shincheonji Church of Jesus after a parishioner left a hospital at least four times to attend services before being diagnosed with the virus.

South Korea has the second-highest number of confirmed cases worldwide, following behind China. But there have been large recent outbreaks on multiple continents. In particular, large numbers of novel coronavirus cases have been reported in Iran (593 cases) and Italy (889 cases).

23 cases have been identified in the UK, including one Saturday with similarly unknown origins as the US cases discovered Friday.

France has banned public gatherings of more than 5,000 people after announcing new outbreaks, bringing their count up to 73 confirmed cases.

A confirmed case in Lagos, Nigeria — the largest city on the African continent — has also sparked alarm.

While there is still plenty unknown about the novel coronavirus (including how exactly it spreads and how deadly it is), the CDC has warned communities to prepare for it to spread in the US.

Experts say US citizens should not panic, but that there are good ways to protect oneself. That includes, yes, washing your hands. But wearing a face mask isn’t helpful if you aren’t sick (although it’s a good idea to wear one if you are). And, if possible, experts have advised stocking up on a few weeks worth of supplies as well as making a plan for what you would do if you or your family were kept from school, day care, or work.