By MIKE STOBBE

NEW YORK (AP) — A second wave of flu is hitting the U.S., turning this into one of the nastiest seasons for children in a decade.

The number of child deaths and the hospitalization rate for youngsters are the highest seen at this point in any season since the severe flu outbreak of 2009-10, health officials said Friday. And the wave is expected to keep going for weeks.

Experts say it is potentially a bad time for an extended flu season, given concerns about the new coronavirus out of China, which can cause symptoms that can be difficult to distinguish from flu without testing.

If coronavirus were to begin spreading in the U.S., there could be confusion about whether people are getting sick with it or the flu, said Dr. William Schaffner, an infectious-diseases expert at Vanderbilt University.

This flu season got off to its earliest start in 15 years, with surges of flu-like illnesses seen in parts of the South as early as October. Most cases were caused by a type of flu that usually causes substantial infections only in the spring, at the tail end of the flu season.

That wave peaked in late December and dropped steadily for weeks afterward.

But a second surge began in late January. Last week saw another rise in the percentage of doctor’s office visits that were due to flu-like illness, according to the U.S. Center for Disease Control and Prevention.

“We have not yet peaked for influenza. We are still on our way up,” Dr. David Weber, a University of North Carolina infectious-diseases specialist, said of the patient traffic in Chapel Hill.

Overall, the CDC estimated that 26 million Americans have gotten sick with flu this past fall and winter, with about 250,000 flu-related hospitalizations and around 14,000 deaths.

The viruses behind both waves can be hard on children and young adults. But they aren’t considered as dangerous to retirement-age people — good news, since most flu deaths and hospitalizations each winter occur in the elderly.

In fact, the overall death and hospitalization rates this season are not high “because we haven’t seen the elderly as involved in this flu season,” said the CDC’s Lynnette Brammer.

But 92 flu-related deaths have already been reported in children, a higher total at this point of the year than in any season in the past decade. And the hospitalization rates also are far higher than what’s been seen at this point.

The CDC said the reason is that two strains of the flu that are tough on children are spreading in the same season.

The health agency is expected to release an estimate next week of how effective the flu vaccine has been.

So far, only 15 U.S. cases of the coronavirus have been confirmed, and no deaths. All but two of the cases were in people who had traveled to Wuhan, China, the epicenter of the international outbreak. The remaining two were spread from travelers to their spouses.

Schaffner said that for the time being, it is easy to determine a likely coronavirus case by asking about a patient’s travel history.

It’s possible that concern about the coronavirus has led some people with flu symptoms to to to the doctor for testing this year, whereas they might have just stayed home in other years, Brammer said. But there is nothing in CDC data that shows that’s been happening, she added.

Health officials this week said they will be using five public health labs that usually test for flu to start also checking for coronavirus. The labs are in Chicago, Los Angeles, New York, San Francisco and Seattle. When a specimen tests negative for flu, it will then be tested for coronavirus, the CDC’s Dr. Nancy Messonnier said Friday.

By YANAN WANG

BEIJING (AP) — China on Thursday reported a sharp spike in deaths and infections from a new virus after the hardest-hit province of Hubei applied a new classification system that broadens the scope of diagnoses for the outbreak, which has spread to more than 20 countries.

Japan reported its first death, a woman in her 80s who had been hospitalized since early February. She is the third confirmed fatality outside of mainland China, after deaths in the Philippines and Hong Kong.

The new diagnostic approach came on the same day that Hubei and its stricken capital, Wuhan, replaced their top officials in an apparent response to public criticism of how authorities have handled the epidemic.

The death toll in China reached 1,367, up 254 from the previous day. The number of confirmed cases jumped 15,152 to 59,804. The unusually large increases were due to the change in Hubei’s approach.

The total now includes more than 13,000 cases of “clinical diagnosis” in Hubei, which appears to include those based on a doctors’ analysis combined with lung imaging, as opposed to waiting for laboratory test results.

In breaking down the large number of new cases in China, National Health Commission spokesman Mi Feng said Hubei had adopted a revised diagnosis and treatment plan aimed at accelerating the identification and treatment of patients.

That adds a “clinical diagnosis case” classification to identify suspected cases who appear to have pneumonia so that patients can be accepted as soon as possible and treated as confirmed cases, Mi said, adding that should “reduce severe illness and mortality.”

One expert said the changed case definition in Hubei likely speaks to the crush of patients the health system is experiencing and the backlog of untested samples.

“Clearly in Wuhan, the health system is under extreme pressure and so the first priority has to be the patient,” said Mark Woolhouse, a professor of infectious disease epidemiology at the University of Edinburgh.

He said it wasn’t unprecedented for case definitions to rely on doctors’ diagnoses rather than wait for laboratory confirmation, and that these kinds of changes usually happen when there are simply too many patients to process in a fast-moving outbreak.

“I’m not surprised that this has happened given the way the outbreak has been going in China,” Woolhouse said. “You have to be pragmatic and take the concerns of the patient first and treat them as if they already have the disease, even in the absence of lab confirmation.”

China also appointed new high-level officials in Hubei and Wuhan.

Former Shanghai Mayor Ying Yong succeeded Jiang Chaoliang as the ruling Communist Party chief in the beleaguered province, the Xinhua state news agency reported, while Wang Zhonglin took over from Ma Guoqiang as the party secretary in Wuhan.

The appointments follow the sacking earlier this week of two leaders of the provincial health commission. State media also reported that a slew of others were expelled from the party for transgressions related to the epidemic.

The public has widely criticized local officials for failing to respond quickly and decisively to the new virus. Authorities initially assured people that there was little to no risk of human-to-human transmission, a statement that was later retracted. Wuhan residents said hospitals were overcrowded and lacked sufficient medical supplies. Doctors who tried to share information early on were reprimanded by police for “spreading rumors.”

Many countries have implemented travel restrictions on recent visitors to China, which has more than 99% of the world’s reported infections.

In an unprecedented measure to contain the disease, recently named COVID-19, the Chinese government has placed the hardest-hit cities — home to more than 60 million — under lockdown. One district in Shiyan, a city in Hubei, has implemented “wartime measures,” barring residents from leaving even their apartment compounds for two weeks.

According to a local government notice, neighborhood committees will distribute basic necessities at a fixed time and at fixed prices, as well as help residents purchase any medicine they might urgently need.

Xu Min, a resident of Shiyan’s Zhangwan district, said her neighborhood entrance was being guarded by community workers and security staff.

“It doesn’t have too much of an impact on our life, except that we’re not allowed to go out,” Xu said.

World Health Organization spokesman Tarik Jasarevic said the agency is seeking more clarity from China on the updates to its case definition and reporting protocol.

“It is our current understanding that the new case definition widens the net, and includes not only lab-confirmed cases but also clinically diagnosed cases based on symptoms and exposure,” Jasarevic said in an email to The Associated Press.

“The jump in cases today reflects the broader definition,” he said.

An advance team of WHO experts has been in China since Monday. The team is here to “discuss specific arrangements for the China-WHO joint mission with the Chinese side,” Chinese foreign ministry spokesman Geng Shuang said at a daily online briefing.

“The purpose of the joint mission is that experts of both sides can have in-depth communication on the situation and efforts of prevention and control, and come up with advice for China and other affected countries,” Geng said.

In Vietnam, official media reported that a village of 10,000 northwest of the capital, Hanoi, was put in lockdown due to a cluster of cases there.

The online newspaper VN Express cited a senior official of Vinh Phuc province as reporting an increase in cases in Son Loi. Vietnam has confirmed 16 cases, most of them in the province.

Japan’s Health Ministry announced Thursday that 44 more people on a cruise ship quarantined in the port of Yokohama, near Tokyo, have tested positive for COVID-19. The ship has 218 infections among its 3,700 passengers and crew.

Health Minister Katsunobu Kato told reporters five of the patients who were already sent to hospitals for isolation and treatment have severe symptoms and are on artificial respirators or under intensive care.

Another cruise ship, the Westerdam, finally docked Thursday in Cambodia after being turned away by several Asian and Pacific governments. No cases of the viral illness have been confirmed among its 1,455 passengers and 802 crew members, according to operator Holland America Line.

Thailand refused to allow the Westerdam to dock this week after it had already been turned away by the Philippines, Taiwan, Japan and Guam over virus concerns.

The Westerdam began its cruise in Singapore last month and its last stop before it was refused further landings was in Hong Kong, where 51 cases of the viral disease have been confirmed.

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Associated Press writers Mari Yamaguchi in Tokyo; Sopheng Cheang in Sihanoukville, Cambodia; Grant Peck in Bangkok; Maria Cheng in London and researchers Liu Zheng and Yu Bing in Beijing contributed to this report.

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This story corrects the number of confirmed cases in mainland China to 59,804, not 52,526.