Flu Vaccine Mismatch Raises Further Concerns About ‘Twindemic’ With Covid-19

Here’s another reason to maintain face mask wearing, social distancing, and other Covid-19 precautions throughout the next few months. It’s that old nemesis, the flu. This year’s flu vaccine may not be a good match for the main influenza strain that’s now circulating, and flu activity throughout the U.S. has been rising over the past week:

All of this raises concerns that a “twindemic” may soon be happening. In this case, a “twindemic” is not a surge in Mary-Kate and Ashley Olsens, Dylan and Cole Sprouses, or those twins in the movie The Shining who said, “Come and play with us.” Instead, it would be the concurrent occurrence of the ongoing Covid-19 coronavirus pandemic along with a new seasonal influenza epidemic.

So, what could happen with such a twindemic? Let’s see. Imagine more and more and more people going to health clinics and hospitals because of Covid-19, which is kind of what’s happening now:

Next, add to that an increase in folks requiring health care because of the flu, which may be happening already:


Then, consider the fact that many health care professionals around the country have been feeling overwhelmed, exhausted, unsupported, and underappreciated by their employers, workplaces, and society. For example:

If the health care system reaches its breaking point, that’s when problems really start to multiply. When hospitals “run out of beds,” it’s not really beds that are the concern. A bed doesn’t ask you how you are feeling, decide what treatments you should receive, and take care of you. It’s health care professionals. And when they are too overtaxed to take care of everyone, patients with Covid-19 or influenza won’t be the only ones to suffer. Those with other major and life-threatening conditions such as heart disease and cancer can suffer as well.

Oh, and to top it all off, this year’s flu vaccine may offer some protection against influenza but not as much as it has in other years. Take a look at a pre-print posted on MedRxiv that described a study conducted by researchers from the University of Pennsylvania Perelman School of Medicine, Scripps Research Institute, and Johns Hopkins Bloomberg School of Public Health. The senior author of the study, Scott E. Hensley, PhD, Professor of Microbiology at the University of Pennsylvania, described the study’s findings in the following tweet thread:

Hensley refers to a mismatch between the flu virus strain in this year’s flu vaccine and the H3N2 strain of influenza that is currently circulating. Each year in advance of the flu season, experts try to predict based on available evidence what strains of influenza will be circulating later on during the flu season. This can be quite a guessing game, sort of like trying to guess which TikTok fad will go viral. Some years, the experts get it right and there’s a good match between the strains in the vaccine and those that end up circulating. Other years, they miss the mark by a bit or even by a lot. This year they may have missed the mark by a fair amount. As you can see in the tweet thread, the study found differences in the hemagglutinin (HA) protein that’s on the surface of the circulating H3N2 influenza strain from the HA protein that’s on the surface of the strain in the vaccine:

Moreover, their lab experiments found that the antibodies generated by the flu vaccine don’t seem to neutralize the circulating version of the H3N2 flu virus very well:

Thus, this year’s flu shot may be a bit like a small thong (as opposed to an enormous thong). It’s certainly better than nothing and can offer you some protection. But it can leave you still quite exposed.

Of course, take anything said by a pre-print with thong-full of salt. A pre-print is not the same as a peer-reviewed publication in a reputable scientific journal.

Nevertheless, this study is a reminder that you shouldn’t solely rely on vaccination against the flu for protection, just like you shouldn’t rely solely on underwear when on a job interview or anywhere else in public. It’s better to be vaccinated than not. But vaccination will never offer you 100% protection.

That’s why maintaining other precautions such as face mask wearing and social distancing over the next several will be very important. This can slow the spread of not only the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants but different versions of the influenza virus.

Some people have been falsely been claiming that Covid-19 is the same thing as the flu. A side-by-side comparison will show that Covid-19 can produce very different problems and has had a significantly higher case fatality rate. The concern is that actually seeing them side-by-side this Winter could lead to more than twice the trouble.

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