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By Julia Ries
- Two flu strains are overlapping each other this flu season.
- This means you can get sick twice from different flu strains.
- While the flu vaccine isn't a perfect match, it's the best defense against the flu.
To say this flu season has been abnormal is an understatement.
For one, the flu season got its earliest start in 16 years.
Up to 18 million people have gotten the flu this year, according to the Centers for Disease Control and Prevention's (CDC) latest estimates. Up to 210,000 people have been hospitalized and thousands have died, including 39 children.
We're also seeing B strains of the flu dominate, something that hasn't happened in the United States in nearly 30 years.
And, unfortunately, the vaccine missed the mark with B/Victoria, the most common strain we're seeing this year. The CDC believes the shot only covers about 58 percent of B-linked cases.
Now, halfway through flu season, A strains are picking up, increasing the odds we'll have a "double-barreled flu season," in which two strains strike back to back — a pattern health experts say is extremely rare.
Between the early start, rise in B strains, and recent spike in A-strain illnesses, this flu season officially has infectious disease experts stumped.
"This season has turned a lot of [what we know about flu] on its head," said Dr. William Schaffner, an infectious disease specialist with Vanderbilt University Medical Center and the medical director at the National Foundation for Infectious Diseases. "There's a lot we know, and even more we don't know about flu."
Double-Barreled Flu Season
A double-barreled flu season occurs when two flu outbreaks overlap one another, a pattern which is very unusual, according to flu experts.
Last year, for example, we saw A/H1N1 infections peak early, followed by another wave of A/H3N2 infections.
Though the predominant strains are different this year, we're seeing the same pattern play out: Activity took off with B/Victoria and now that second wave of A/H1N1 is coming for us, according to Schaffner.
"Around the country, my colleagues and I are seeing H1N1 come up strong, and it's now about 50-50 [with B/Victoria]," Schaffner told Healthline.
The most worrisome part of a double-barreled flu season is that you can get sick twice.
Just because you caught a B-strain flu doesn't mean that you're immune from the A strains.
"There will be the rare person who gets two flu infections in the same season — one with B and one with H1N1," Schaffner said.
Though there will be some protection within each strain — in that contracting an A strain will protect you against other A strains, and B strains will protect against other B's — there's not much cross protection.
A double-barreled season also means we're more likely to see a prolonged influenza season.
Read more: https://www.ecowatch.com/flu-twice-this-year-2644859184.html