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  • Flu cases are on the rise in the United States.
  • Last month, the WHO warned that this year’s flu vaccine may not be as effective at stopping the flu as experts had hoped.
  • Flu season usually peaks in February.

About a month ago, the World Health Organization (WHO) announced that this year’s flu vaccine might not be as effective as we’d hoped. The four strains it was designed to target didn’t match the strains circulating in the Southern Hemisphere: influenza A (H3N2) and influenza B (Victoria).

As expected, those two strains that hit the Southern Hemisphere are now striking the United States — in Louisiana, Alabama, Georgia, Mississippi, South Carolina, Texas, and Puerto Rico.

The start to this year’s flu season has been a slow one, at least in much of the country.

As of Friday, November 15, there have been three pediatric deaths, according to the Centers for Disease Control and Prevention’s (CDC) weekly flu report. About 2.3 percent of visits to a healthcare provider were for an influenza-like illness, which is below the national baseline of 2.4 percent.

In addition, about 4.9 percent of all deaths were due to pneumonia and influenza, also below the epidemic threshold of 6 percent.

“Based on today’s surveillance report, flu activity is increasing nationally with significant spread of H1N1, H3N2, and influenza B/Victoria viruses. Different viruses are predominate in different places and among different age groups. Parts of the country are seeing an early start to their flu season, but other parts of the country are still seeing little activity,” Kristen Nordlund, a spokesperson for the CDC, told Healthline.

Health experts agree that it’s still far too soon to predict exactly how flu activity is going to pan out this year.

“So far, it is still too early to state whether this year’s flu season will be more or less than what is typical. It is important to note that even in a typical year, the flu has substantial impact,” says Dr. Richard Martinello, a Yale Medicine infectious diseases expert.

Flu season usually peaks around February, but surveillance charts are showing that flu activity is starting to pick up around the country.

We’re currently seeing three strains in the United States:

  • A (H3N2), which circulated during the latter half of last year’s flu season
  • B/Victoria, the strain the Southern Hemisphere saw
  • H1N1, which we typically see this time of year

According to Dr. Amesh Adalja, an infectious diseases specialist and senior scholar at Johns Hopkins Center for Health Security, the illnesses the strains cause share similar symptoms — fever, chills, cough, and body aches.

“Influenza B is a strain of flu that can cause ordinary flu-like symptoms and severe illness as well (though many people erroneously believe it to be less severe). The differences between influenza A and B are not really apparent clinically,” Adalja said.

However, just because we’re seeing these strains now doesn’t mean they’ll dominate all season. Even when we think we know which strain is going to pop up, influenza viruses can quickly change and swing another way, according to Yale Medicine.

In addition, flu activity tends to vary greatly across different regions, Martinello noted.

Last year’s flu season was relatively moderate. Flu activity didn’t start increasing until November, then it peaked in February and continued through April, making it the longest season in 10 years, according to the CDC.

At this point last year, influenza A viruses (H1N1) were most commonly reported, which is the norm, according to a past CDC flu report. This year we’re seeing more influenza B strains, which again could change at any point.

“It’s too early to say what one group of viruses will predominate this season, but influenza B/Victoria viruses are nationally predominant at this time. It’s unusual for there to be this much influenza B activity at this time of year,” Nordlund said.

By November 17, 2018, there was one pediatric death and about 1.9 percent of hospital visits were due to influenza, which is slightly lower than what we’re seeing this year.

Even if the predicted vaccine mismatch prevails, it’s still crucial to get the vaccine.

“We’re moving into flu season; we are seeing, and will continue to see, flu illness and some severe flu outcomes, which is why getting a flu vaccine now is so important,” the CDC said, adding that anyone can search local places to get the vaccine at Vaccinefinder.org.

A vaccine mismatch could fuel the severity of the season, but the vaccine can still help with symptoms.

“About 60 percent of the virus characterized so far has been influenza B, and the majority of that strain is not covered by the vaccine. That said, the flu vaccination is still the best way to prevent flu. Even if the vaccine is not a perfect match, [it] may still provide some protection from getting severely ill,” says Dr. Eric A. Weiss, emergency medicine physician at Stanford Health Care.

The vaccine can lower your risk of complications, including pneumonia and hospitalization, according to Adalja.

On top of that, Weiss says your best protective measures are frequent handwashing and staying about 6 feet away from someone who is sick or coughing.

Flu season is just getting started. Now’s the time to take the necessary steps to protect yourselves against influenza.

This year’s flu vaccine might miss the mark with two of the strains currently hitting the United States. Still, it’s been a slow start to the flu season, with little activity in much of the country and moderate activity in the Southwest and Southeast.

Flu experts say it’s too early to know exactly how flu season will pan out — and even if the vaccine is a mismatch, you should still get immunized to significantly reduce the severity of symptoms.