A severe variant of the influenza virus has produced a powerful start to the 2018 flu season.

While flu season always occurs during the colder months, it’s hit a little earlier than usual in North America.

And this year’s H3N2 strain is packing some punch.

The Centers for Disease Control and Prevention (CDC) reports the number of states with widespread flu activity has jumped from 23 to 36.

The illness has already hit Texas hard.

Last week, Dallas County health officials reported a fifth flu-related death.

Officials in southeastern Texas were reporting a rising number of flu cases in mid-December.

Arizona health officials said in early December that the state had already had more than 1,100 cases of influenza. The illness has hit all 15 counties in the state.

All this has health experts concerned.

“We’re all tightening our seatbelts,” Dr. William Schaffner, chair of the department of preventive medicine at Vanderbilt University Medical Center, told Healthline. “We anticipate a moderate to severe influenza season. It started early, it’s all over the United States, and it’s climbing rapidly.”

As always, health experts — from infectious disease specialists to national and international health organizations — are urging the public to get their flu shots and take other steps to prevent transmission of the flu.

The year of H3N2

Since its first detection in humans in 2011, the H3N2 family of flu viruses has played a role in every flu season.

Experts knew early on that H3N2 would likely hit the Northern Hemisphere hard this winter.

The virus has already played a big role in what turned out to be a bad flu season in Australia. The flu vaccine used to treat people in the Southern Hemisphere was reportedly only 10 percent effective this season.

Complicating matters is the fact that H3N2 is a nastier strain than many of the viruses seen in the past.

“We know that, historically, the H3N2 strains are more severe,” said Schaffner. “They tend to result in more complications of flu: pneumonia, having to be hospitalized, and actually dying — that’s number one.”

“Number two, H3N2 has its most severe impact in older persons, and older persons are simply more likely to get all these complications,” he continued. “The third thing is that our vaccine, even though it’s targeted to H3N2 very nicely, those vaccines are not optimal against H3N2, particularly in older persons. So, all of those things are going to conspire to make it a moderate to severe flu season.”

Schaffner’s team at Vanderbilt is one of 12 across the United States that works under the CDC’s sponsorship to do surveillance for serious cases of influenza.

These are defined as verified flu cases serious enough to require hospitalization.

Representative statistics are tough to come by, as most cases of influenza don’t get laboratory documentation.

But Schaffner says that he and his colleagues across the country have seen the number of patients with the flu shoot up since December.

“Everyone is braced, and folks from the minute clinic to doctor’s offices to emergency rooms and, indeed, hospitals are anticipating that we’re going to have a very busy early winter season — through January and into early February, that’s when we think flu is going to peak,” said Schaffner. “That means that we all have to be ready with our scheduling to take care of patients who come into our emergency rooms.”

Vaccination more important than ever

The advice from health experts hasn’t changed.

If you want to avoid getting the flu, the number one thing you can do is to get vaccinated.

“It’s not too late to get vaccinated,” said Schaffner. “Hurry up and get vaccinated. Don’t linger. Go to your pharmacist, your doctor’s office, your clinic, and get vaccinated.”

Despite data showing that the flu vaccine isn’t optimal against the H3N2 strain, it’s still the best vaccine we currently have.

“Even if it doesn’t protect you completely, it will make the illness milder,” said Schaffner. “So if you do happen to get the flu despite getting the vaccine, you’re less likely to get the complications of pneumonia, you’re less likely to have to be hospitalized, and you’re less likely, frankly, to die. So we have to recognize that even though we don’t have a perfect vaccine, it still is pretty darn good.”

It’s also worth noting that, despite H3N2’s significant role this flu season, it’s not the only strain out there.

For those milder, less common flu strains, the vaccine is considerably more effective.

A final incentive to get vaccinated is to protect friends and family.

“[Getting vaccinated] makes it less likely that you’re going to spread the virus to your friends and family and co-workers,” said Schaffner. “No one likes to be, as I say, ‘the dreaded spreader.’ Nobody wants to be the source. So there are a bunch of reasons, still, to get vaccinated — and do it quickly.”

For people who do come down with the flu, Schaffner recommends promptly calling their healthcare provider. They may prescribe an antiviral that can lessen the effects of the illness.