Experts are unsure of the severity of this year’s flu season

The rate of hospitalizations for the flu in the United States has hit the highest levels since health officials started recording this data in 2010, according to the U.S. Centers for Disease Control and Prevention (CDC)—a sign this year’s flu season could be among the worst in more than a decade.

One reason may be a strong influenza virus, which was also seen last year and three years ago. The 2014-15 flu season was categorized by the CDC as a “high severity season,” predominated by the H3N2 influenza virus, which is also predominant in the current season. “It is clear H3N2 is more virulent, but we don’t really understand why,” said Professor Arthur L. Reingold, head of the Epidemiology Division at UC Berkeley.

The number influenza deaths is another indicator measuring the severity of a season. During the 2014-15 flu season, 83 people younger than 65 years old died from flu in California, according to the California Department of Public Health (CDPH). Eleven flu deaths were counted in Alameda County, and one in Contra Costa County. For this season, so far the CDPH has counted 97 deaths under age 65 (as of January 20), with 7 in Contra Costa County and 3 in Alameda County.

While Dr. Erica Pan, director of Alameda County’s Division of Communicable Disease Control and Prevention, finds this season much alike 2014-15, Paul Leung from Contra Costa County’s Communicable Disease Program said he isn’t sure yet.

National experts are also cautious: “We don’t know what the season is going to end up like. … But it’s tracking at the same level as 2014-15, which was the last high severity season that we had,” stated Dr. Dan Jernigan, director of the Influenza Division in the National Center for Immunization and Respiratory Diseases at CDC, in a press briefing in the end of January.

“People die of the flu every year,” said Reingold, “and the only question is how many.” A common mistake by the public is to think flu is like a cold – “but it’s not, it is a bad disease,” he said. As flu and cold have similar symptoms, it can be difficult to tell the difference between the two diseases. According to the CDC, symptoms of flu can include fever, sore throat, muscle and body aches and fatigue. In comparison, cold symptoms are milder and people are more likely to have a runny or stuffy nose.

As protection from the flu, it is not too late to get this year’s flu shot. The shot contains vaccination for influenza H3N2, H1N1 and two influenza B lineages. That’s “a lucky guess,” according to Reingold, as every February vaccine manufacturers more or less guess which strain will be predominant in the next season and needed in the vaccination. Even though the guess for this season was right, the vaccination does not necessarily prevent someone from getting the flu, but reduces the likelihood that they will get severely sick or be hospitalized. Leung compares the effectiveness of flu shots to seat belts: “It won’t protect you from bruises and scratches, but from dying.”

Even though flu activity is beginning to go down in some parts of the U.S., the season is not over yet. As the flu began earlier than usual, Pan thinks it already peaked in the last week of December and the first week of January, and will decrease in the upcoming weeks.

But Leung is very unsure if the season has peaked yet or not. “And even after the peak, it will continue,” he said.