New influenza strain of influenza, H3N2, new disease approaching the winter

The flu season is likely to peak, but health officials are seeing a recent wave of illnesses caused by more serious flu.

The flu was reported to have spread to 48 states last week, up from 49, the Center for Disease Control and Prevention reported on Friday in its latest report on this winter's influenza season. Federal influenza forecasters say there is a 90% chance that the flu season has reached its peak.

But experts are also monitoring the increase in the number of illnesses caused by some sort of influenza virus that tends to cause more hospitalizations and deaths, especially among the elderly.

It is not unusual for many influenza strains to spread in the country at the same time, but one type usually predominates.

This season, a less severe strain was the most common cause of influenza. But over the past two weeks, more diseases have been linked to a strain that tends to cause more deaths.

Last week, about 60% of the influenza virus samples tested were the most problematic strain known as H3N2 type A.

Uncertainty about the type of H3N2 virus that will spread later this year has recently led the World Health Organization to postpone its decision as to which strains should be included in the influenza vaccine for next season .

Last season, about 80,000 Americans died of the flu and its complications, the largest number of deaths in at least four decades. According to the CDC, in recent years, the number of deaths related to influenza has ranged from 12,000 to 56,000.

CDC officials estimate that there have been about 20,000 to 30,000 influenza-related deaths so far this winter.

They also believe that there have been about 300,000 influenza-related hospitalizations and about 25 million cases of influenza.

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The Associated Press Science & Science Department is supported by the Howard Hughes Medical Institute's Department of Science Education. The AP is solely responsible for all content.