The flights between LAX and Tokyo Narita will remain suspended until at least April 24.
The airline also suspended Tokyo Narita service from Houston and Chicago. United flights to Tokyo's Haneda Airport from San Francisco have not been affected.
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Meanwhile, United extended its already-in-place flight suspensions to other regions.
"We will stay in close contact with the CDC and other health organizations as we continue to evaluate our schedule,'' according to an online update from the airline.
The airline is waiving some flight-change fees and is also offering refunds on some flights to select cities. Find more information from United here.
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Several other airlines have already suspended or reduced flights to China and Hong Kong, but United is believed to be the first to halt flights to Japan and Singapore.
Earlier Friday, the World Health Organization raised its coronavirus risk assessment to "very high" as cases outside of China continue to increase.
Officials say more than 20 vaccines are being developed worldwide with results from clinical trials expected in a few weeks.
About half of the United States' coronavirus cases are in California, where more than 8,400 people are being monitored in 49 different jurisdictions after arriving on flights from Asia, state health officials said.
Officials say there are 33 confirmed cases currently in California, but officials reiterate the risk to the public remains low.
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A new case of coronavirus was detected in Northern California in a woman who has not traveled overseas since the outbreak began. This suggests the virus could be spreading locally, person-to-person, the CDC said.
It is unknown how the woman contracted the virus. If it was contracted in the United States, it would be the country's first case of it spreading here, as opposed to being exposed overseas.
CORONAVIRUS UPDATES: Track the latest developments at abc7.com/coronavirus
City News Service contributed to this report.