BEIJING - Confirmed cases of a new pneumonia-causing coronavirus have neared 64,000 in China, with the death toll in the mainland rising to 1,380, China's health authorities said Friday.

The cases included 1,716 health workers, six of whom have died as a result, they also said, raising alarm about an increase in infection cases among medical workers.

The authorities said 5,090 new cases were reported as of Thursday, bringing the total in the mainland to 63,851.

The death toll had reached 1,483 in an announcement earlier in the morning, but it was revised down after the authorities corrected their tallies.

In Wuhan, the capital of the central Chinese province of Hubei at the center of the outbreak, 88 additional deaths were reported. Infection cases and deaths attributed to the virus have been concentrated in the regional transport and business hub.

A National Health Commission official told a press briefing on Friday that as of Tuesday, 1,102 health workers, including doctors, had been infected in Wuhan, underscoring the risks they face in treating a flood of patients amid a shortage of medical supplies, including protective gear.

(A man disinfects outside Beijing Station on Feb. 13, 2020.)

The virus that causes the disease now known as COVID-19, is believed to have originated in Wuhan late last year.

On Thursday, the central government held a high-level meeting chaired by Premier Li Keqiang in which a further strengthening of the "control of outbound traffic" from Hubei Province and Wuhan was stressed to prevent the infection from spreading outside, according to official media.

Although people in Hubei were expected to return to work Friday after an extended Lunar New Year holiday from late January, the province on Thursday extended the break by another week until next Thursday.

Honda Motor Co. said Friday it will postpone the restart of operations at its four-wheel vehicle factories in Wuhan by one week to Feb. 21 in line with the provincial policy, with production due to resume on Feb. 24 or later.

As drug companies around the world race to find a cure for the COVID-19 virus, a Chinese state-owned biotechnology company said late Thursday that it has developed blood plasma to treat critically ill patients, and that it has proven effective.

China National Biotec Group Co. said in a statement posted on WeChat that once the plasma collected from some recovered patients was given to some critically ill patients, they showed improved symptoms within 24 hours, such as reduced inflammation and higher blood oxygen levels.

Thursday had marked the highest daily toll from the virus in China, with an excess of 200 for the first time, after authorities in Hubei changed their diagnostic criteria to include clinically diagnosed cases in their tallies.

The change was explained initially as a way to bring the criteria in line with national ones, but the Chinese government said later Thursday that the measure, which classifies some of the previously suspected cases as confirmed ones, is being taken only in Hubei to treat more patients more quickly.

In neighboring Vietnam, where 16 infections have been confirmed so far, a quarantine began Thursday in a rural community of over 10,000 people in the northern province of Vinh Phuc, after 11 of the cases were found there, local media reported.

The quarantine in Son Loi is slated to last at least two weeks. Most of the 11 patients were employees of a Japanese company operating in the province. They had been in Wuhan for training until last month.

Outside mainland China, more than 500 cases have been reported, such as in other parts of Asia, Europe and North America. Japan on Thursday reported its first known death from the virus, marking the third death reported outside mainland China.

Hong Kong and the Philippines have each reported one death.

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