Four children in the state died in January of the flu, a contagious illness that has left none of New York’s 62 counties untouched, state Department of Health officials said.

Details on the children’s age, gender and county of residence were not released. None of the deaths occurred in Nassau or Suffolk counties, officials at the health departments in each county confirmed Monday.

Public health epidemiologists have long considered pediatric flu deaths to be a key benchmark of a severe flu season.

The state Health Department described the status of influenza as “widespread.” The agency has not declared an epidemic.

Nassau and Suffolk counties, New York City’s five boroughs and the 55 other counties have had cases of flu confirmed by the state laboratory, the department said.

Dr. Aaron Glatt, who chairs the Department of Medicine at South Nassau Communities Hospital in Oceanside, said getting a flu shot still is a wise move for those who have not been immunized, even though it is February.

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“Absolutely a good idea to get vaccinated,” said Glatt, a specialist in infectious diseases. “It’s not too late, and it’s smarter to do it than not to do it.”

The national Centers for Disease Control and Prevention recommends that everyone 6 months of age and older be vaccinated against the flu, with the season running from October through April.

Experts at Nassau University Medical Center in East Meadow who track flu viruses on the move throughout Long Island said influenza type A is the leading strain causing local infections. Flu trackers base their findings on specimens collected from NUMC patients and from samples of patients seen by doctors elsewhere on the Island.

“We’re primarily seeing H3N2 in the local area, which is the same [strain] causing the flu throughout the rest of the United States,” said Dr. Rachel Robbins, who chairs NUMC’s pathology department. H3N2 is a type A strain.

The H and N designations are initials for two proteins — hemagglutination and neuraminidase, both of which stipple the surface of a flu virus. H is responsible for binding the virus to cells in the upper respiratory tract. N allows the pathogens to break free from infected cells and move into unaffected cells during the infection cycle.

Robbins said there also is evidence locally of H1N1, which is another A strain, and a B strain of flu. Neither is as prevalent as the dominant H3N2 strain, she said.

“Long Island has had more than 10 cases for every 100,000 people in the population,” saud Robbins, who with Dr. Gary Leonardi, the head of virology at NUMC, tracks the wide variety of wintertime viruses circulating regionwide.

This year’s flu vaccine is not a close match to the primary viral strain in circulation, Glatt said, but it’s still better to be vaccinated because if exposed to the virus, the severity of the infection tends to be lesser for those who have been immunized.

The nasal spray vaccine is not available this year because CDC tests found that it had only 3 percent effectiveness in a pediatric study of youngsters between the ages of 2 and 17. Doctors instead are recommending a flu shot.

Vaccination also can be a lifesaver for high-risk patients, Glatt added.

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A study last week in the American College of Cardiology’s heart failure journal indicated the flu and pneumonia vaccines together can improve the quality of life — and extend life — for heart failure patients. In heart failure, the organ is severely weakened and cannot pump enough blood to meet the body’s oxygen demands. The disorder affects about 6 million people nationwide, most of them elderly.

New York is one of 15 states reporting high flu activity, according to the CDC, which estimated seven pediatric deaths nationwide as of Jan. 27, the most recent update of the agency’s statistics. In mild flu seasons, there are no pediatric deaths, agency officials said.

During last year’s flu season, three pediatric flu deaths were reported in New York, all in April, state Health Department data show.

California health authorities also have defined their flu status as widespread; they have reported one pediatric death. That state’s public health officials are calling the flu season there “more severe than last year.”

The outbreak there is so pervasive that some hospitals are running out of beds.

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“Some acute-care hospitals in California are full and have diverted patients to other facilities,” Dr. Karen Smith, the state’s chief public health officer, said in a statement.