It’s beginning to look like a lot like a flu Christmas. Surges of influenza are hitting parts of the U.S. hard, and the worst is yet to come.
Various regions of the country have reported a dramatic climb in cases lately, including New York City. Overall activity is on the rise nationwide, as are flu-related hospitalizations and deaths. This season is being fueled by an unexpected strain of “super flu.”
The “super flu”
A typical flu season is nothing to brush off. Annually, influenza sickens millions of Americans, hospitalizes hundreds of thousands, and kills tens of thousands. But this winter has brought along an especially nasty variant of the H3N2 flu known as subclade K.
The variant is noticeably different on a genetic level from the flu strains scientists predicted would be circulating this season, meaning our vaccines aren’t as effective against it as usual. Subclade K emerged towards the end of the winter in the Southern Hemisphere, and since then, it’s quickly supplanted other strains of H3N2 and other flu viruses in general worldwide.
K already caused the flu season to arrive weeks ahead of schedule in European and Asian countries. In the UK, it’s helped cause a spike of hospitalizations and an “unprecedented wave of super flu.” And now it’s clearly making its mark in the U.S.
Several school districts have had to temporarily shut down due to flu outbreaks, while some hospitals are reporting an alarming rise of cases. Data collected from the NYC Health Department shows that nearly 10,000 emergency room visits of flu-like illness were reported last week—the largest weekly peak seen in at least a decade.
According to the CDC’s latest flu surveillance data (covering up to Dec. 13), the majority of new infections are being caused by H3N2. Flu activity is “very high” or “high” in 17 regions of the U.S., including NYC, and “moderate” in another 8 jurisdictions. Two more pediatric deaths were reported that week, rising the total to 3 deaths so far this season. And we almost certainly haven’t reached the peak yet.
What to do
There are some silver linings to this bad flu season.
For starters, subclade K doesn’t seem to have any mutations that make it more likely to cause severe illness compared to other H3N2 strains. And though the seasonal flu vaccine is mismatched to the variant, it’s not worthless. UK data has found that the vaccine is still providing significant protection from serious complications, especially in children.
This means that vaccination remains a crucial tool against flu this winter. So it’s still worthwhile to get your flu shot even now, though you should keep in mind that it takes around two weeks for the vaccine’s protection to kick in.
You should also practice good hygiene like regularly washing your hands, trying to stay home if you’re sick, and potentially wearing a mask in higher-risk situations for added protection. Well-fitting, high-quality masks such as a KN95 or N95 are the most effective.
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