Flu prevalent in 49 states, but leveling off

• Maine is the only state not hit
• New York City and 26 states report high activity
• The number of cases is rising in the West

Flu seems to be leveling off nationally, though some parts of the country are still showing increases, the Centers for Disease Control and Prevention said Friday. In general, the South, Southeast, New England and the Midwest are declining. The Southwest and the Northwest are rising.

So far this flu season, 37 children have died from the virus, according to CDC's weekly FluView. Flu is prevalent in 49 states — Maine is the exception — and high in 26states and New York City. The level of flu activity — high, moderate, low or minimal — is an indication of what percentage of outpatient visits in a state are for a flulike illness, compared with months when there is no flu.

During the week of Jan. 13 through 19, 9.8% of deaths reported in CDC's 122 Cities Mortality Reporting System were due to pneumonia and influenza. That's above the epidemic threshold of 7.3%. The rate of deaths linked to pneumonia and flu the week before was 8.3%. Most deaths were in people 65 and older.

This year's flu season got off to an early start, ramping up in late December, almost a month earlier than usual, according to CDC Director Thomas Frieden. The flu strains circulating in the United States this season also appear to be causing more severe illness, especially compared with last year's mild season. One indicator doctors look at is the number of children who die each year from the flu, the only national death statistics which the CDC keeps for influenza. This year, flu has already killed 37 children, whereas last year the entire season's toll was 34 children.

Now the flu appears to be slowly waning. One of the signals CDC uses to indicate the official start of flu season is when more than 2.2% of all visits to the doctor nationwide are for flulike illnesses. In non-flu months, such as the summer, about 1% of doctor visits are for flulike illnesses. Last week, the number of people visiting doctors and clinics for influenza-like illnesses was 4.3%. The week before that it was 4.5%, and for the first week of January it was 4.3%. For the last week of December, the rate was 5.6%.

The flu emergency that several East Coast cities including Boston and New York had declared over the past two weeks has passed, but flu cases are still "going strong," said Jim Heffernan, chief of primary care at Boston's Beth Israel Deaconess Medical Center. While he's not seeing overflowing emergency rooms as he was at the beginning of the month, the hospital is still getting "several hundred calls a day" for people who are suffering from the flu.

"It does seem to have peaked here, but there are still a lot of sick people out there," he said. "Far more than last year, probably more than we've seen since H1N1," he said, referring to the pandemic flu strain that struck the world in 2009. In that outbreak, an estimated 24% of people worldwide got the flu, according to a paper published this week in the journal Influenza and Other Respiratory Viruses.

While shortages of flu vaccine are still popping up around the country as the flu hits localized areas, there is still vaccine available, CDC said. As of Jan. 18, a total of 133.5 million doses of influenza vaccine had been distributed to vaccine providers in the United States for this season.

About half of pharmacies that ran out of flu vaccine were able to get more, according to a survey done Jan. 14-16 by the National Influenza Vaccine Summit, a public health group that works on flu vaccine issues.