Masks Depart, 'Stomach Flu' Arrives. Enough Already!

By Josh Bloom — Feb 16, 2023
Is it really asking too much to have a few weeks of microbiological peace? Apparently, it is. Just as we are finally chucking the masks, upchucking is waiting in the wings. There are some signs of a bad norovirus ("stomach flu") season. Lovely.
Image: Wikimedia Commons

At the risk of being accused of grotesque anthropomorphism, I nonetheless maintain that viruses are evil. And intelligent.  After three years of COVID restrictions, many rational, some ridiculous, many Americans, because of  relaxed rules (in the US and globally) are tossing their masks and relaxing a little because COVID is more or less "under control." (1)

Don't believe for a second that the collective virus population wasn't aware of this. In the perpetual battle against human immune systems viruses are way ahead. The little bastards not only possess a variety of devious methods of overcoming drugs and vaccines, but they can do so even before being exposed to the drug. And, of course, just to screw with our collective psyches, I maintain that they planned all of this, perhaps at their 2022 "Hey Viruses - Let's Humiliate Mankind" annual meeting, which, according to my sources, was held in an undisclosed duodenum in Cleveland. The outcome? "Let's throw a really bad norovirus season at them." (Just to placate the Audubon Society, they also threw in an avian flu epidemic, but as the saying goes, that's for the birds.)

So far they are sticking to the plan. The numbers in the US aren't compelling, at least yet; it's way too early to predict how bad the year will be two months prior to "Prime Time Spew Season." (Figure 1)

Figure 1. (Left) A graph that Superman couldn't read. A comparison of the number of outbreaks reported over the past three winters (Right) An enlarged portion of the graph shows a 30% increase in reported outbreaks comparing 1/22 to 1/23. The 2021 non-season can be attributed to COVID isolation and closed restaurants. Source: CDC NoroStat Data (A seasonal year’s line that consistently falls above the gray area might indicate unusually high norovirus activity.

Although the outbreak numbers for 2023 (red line) are generally higher than those of 2022 this graph provides only weak evidence that this norovirus season in the US will be substantially different from last year. But there is more compelling (and troubling) evidence from across the Atlantic, especially in the UK. 

A cup of tea won't help this

Britain is getting hit very hard. According to the UK Health Security Agency (UKHSA) there has been a 66% increase in cases in weeks 1-4 of 2023 compared to 2022 (red line with yellow oval, below). Perhaps more disturbing is that the number of lab-confirmed cases in people 65+ is higher than in more than a decade. The trend difference is not subtle. (Figure 2)

Figure 2. Norovirus laboratory reports in England by week during 2021/2022 and 2022/2023 seasons, compared with the 5-season average. The yellow oval is alarming. The 4th week in January was far worse than the comparable week in the past. Source: National norovirus and rotavirus surveillance reports: 2022 to 2023 season.

BRW, if you think that the naming "system" for COVID variants and subvariants was mysterious, the categorization of norovirus "strains" put COVID to shame. Look at this insanity...

Top: Classification of two bazillion norovirus genotypes. Bottom: enlarged area showing the genotype that is the main cause of hurling. There will be a quiz. Source: J Gen Virol. 2019 Oct; 100(10): 1393–1406. Published online 2019 Sep 4. doi: 10.1099/jgv.0.001318

What does this have to do with the US?

Plenty. Although what happens in Vegas stays in Vegas the same cannot be said for norovirus. It goes wherever it wants. And the main offender, G.II.4, is the same genotype (also called genogroup - don't ask) that is the predominant circulating strain in the US. Roughly 80% of US infections are G.II.4 as seen in Figure 3. So it's not unreasonable to expect that we may soon see a surge on this side of the pond.

(Figure 3) Norovirus genotypes in the US. Source: CaliciNet

Bottom line

There is no guarantee that we will be experiencing what's happening in the UK, but remember the early efforts to contain COVID? The virus won that battle and it will probably win this one too. Evil bastards.

Next: The differences between COVID and norovirus.


(1) "Under control" is a subject term. Even with vaccines and antivirals now available about 3,000 people die every week from COVID. That's a whole lot better than when it was 3,000 per day. Is this "under control?" Who knows?


Josh Bloom

Director of Chemical and Pharmaceutical Science

Dr. Josh Bloom, the Director of Chemical and Pharmaceutical Science, comes from the world of drug discovery, where he did research for more than 20 years. He holds a Ph.D. in chemistry.

Recent articles by this author:
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