Is early flu season tied to influenza type B?

The 2019-2020 flu season in the USA has commenced and may be attributed to the early rise of influenza B – a strain of the virus that typically emerges toward the end of flu season.

Flu activity has been higher than normal for the past month, according to the Centers for Disease Control and Prevention, and continues to rise.

As of Nov. 30, 3.5% of visits to health care providers were due to influenza-like illnesses, considerably higher than the average national baseline of 2.2% but probably not the peak.

This flu season is the earliest this decade that the percentage of visits to health care providers associated with influenza-like illnesses is above the national baseline.

The last time it exceeded the baseline this early, excluding 2009 during the H1N1 epidemic, was the 2003-2004 flu season, when an especially virulent strain of influenza A ravaged the USA.

This year, there have been about 910 deaths, 16,000 hospitalizations, 800,000 doctors’ visits and 1.7 million cases of the flu connected to the 2019-2020 flu season, according to the CDC.

Sixteen states – Alabama, California, Connecticut, Georgia, Indiana, Louisiana, Massachusetts, Mississippi, Nevada, New Mexico,

New York, Pennsylvania, South Carolina, Tennessee, Texas and Virginia – have reported widespread flu.

The South is particularly afflicted by the flu this year, while mid-Atlantic and Northeast states are not as afflicted.

What is influenza B?

More people are being infected with influenza B early in the flu season, said Aaron Milstone, a professor of pediatrics at Johns Hopkins University School of Medicine.

“Typically, you see influenza A as the early wave of the flu, and influenza B starts to show up at the end of the spring,” he told USA TODAY.

“This year, it just flip-flopped.”

There was little influenza B activity last season, according to the University of Minnesota’s Center for Infectious Disease Research and Policy.

It’s unclear, Milstone said, if there is a biological explanation for why influenza B emerges toward the end of the flu season – and why this year is an exception.

Who is affected by influenza B?

The CDC said 62% of positive flu specimens tested by public health laboratories nationwide were influenza B.

It tends to affect children and young adults more severely than its type A counterpart.

Some 46% of children up to age 4 and 60% of children and young adults tested positive for influenza B.

How to prevent influenza B

Milstone’s advice? Get the flu shot – especially before the flu season starts to peak.

The flu vaccine covers influenza A and B, he said, and is recommended by the CDC for everybody older than 6 months who wouldn’t have a harmful reaction to the vaccine.

“Even though some people are concerned that it’s ineffective, it is still by far the best thing you can do,” he said.

During the 2017-18 season, which led to 79,000 deaths related to the flu, the CDC estimated flu vaccines prevented more than 7 million flu cases, 3.7 million visits to the doctor, 109,000 hospitalizations and 8,000 deaths.

Among Milstone’s other advice are these standbys. “People should wash their hands a lot, before they’re eating, touching their face,” he said.

“If people do have fevers, they should be staying at home.”

So far this season, there have been 910 deaths, 16,000 hospitalizations, 800,000 doctors’ visits and 1.7 million cases of the flu connected to the 2019-2020 flu season.

Centers for Disease Control