Covid-19: does a new Omicron variant really cause more diarrhea and vomiting?

“The arrival of the BQ.1.1 variant is not good news. It has the peculiarity of causing diarrhea and vomiting,” pediatrician Rémi Salomon wrote on Twitter in the middle of the night from Monday to Tuesday. The President of the Medical Establishment Committee of the Assistance Publique-Hôpitaux de Paris shares data showing that this new strain of the Omicron galaxy is developing in France.

A few hours later, L’Express published an article on its website with this catchy title: “Covid: diarrhea, vomiting… The new symptoms of the BQ.1.1 variant”.

And yet, at present, there is no reliable data to confirm this. The article from L’Express does not mention any source and is based in particular on a testimony of general practitioner Jérôme Marty, about whom “three patients complained of abdominal pain before realizing they were positive for Covid”.

His colleague Matthieu Calafiore says for his part that he has seen “clearly more digestive disorders” in recent weeks, but “with a wet finger and without indisputable scientific value”. BQ.1.1 represented 6% of the positive cases whose genomic sequence was analyzed at the end of September in France, but it is impossible to know which patients captured this subvariant and not another.

Thai medical website

Above all, digestive problems have always been part of the possible symptoms of Covid-19, while they remain relatively rare. Among people infected with the Omicron variant in December 2021 in England, 4.8% suffered from diarrhea and 6.2% had nausea or vomiting. These disorders were slightly more frequent in cases of infection with the Delta variant (6.6% and 8.9%, respectively).

“Since the start of Covid, we have had people with stomach aches. I have never made the link to BQ.1.1”, thunders Jérôme Marty with Le Parisien.

So where did this claim that digestive disorders had become more frequent with this subvariant come from? Many internet users who often share information about Covid – like Rémi Salomon – have reported it in recent days on Twitter.

In reality, it all starts with an article published on October 5 on an obscure Thai site, “Thailand Medical News”, but subsequently widely shared on social networks. “Early data based on clinical observations from doctors in hospitals as well as genomic sequencing data from the UK, France and Australia show that the new SARS-CoV-2 variants BM.1.1 and BQ.1.1 tend to increase endothelial cells in the digestive tract,” reads the introduction.

“Some Viral Tweets Get Out of Hand”

The article then describes the profile of 14 positive cases, “almost all of whom complained of severe abdominal pain” … without saying where they came from. Still, his conclusions were immediately picked up by many internet users. Rémi Salomon also says that he based himself on various tweets. A certain Xabier Ostale, who is already known to have coined the terrifying and sarcastic nickname “Centaur” in the Omicron BA.2.75 variant, saw his message published on October 10 “liked” by nearly 3,000 internet users.

“He has to be very careful and there is nothing to confirm a change in symptoms. I spent my time saying that we did not have enough data to confirm it,” temporizes the virologist Yannick Simonin, who had previously responded to L ‘Express. “Thailand Medical News is not a reliable source. The site is known to speculate a lot, and these claims are not supported by evidence”, the German scientist Cornelius Roemer is moved, lamenting that “some viral tweets are getting out of control”.

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