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 particularity of causing diarrhea and vomiting, ”wrote pediatrician Rémi Salomon 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 progressing in France.

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

And yet, at this stage, 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 from general practitioner Jérôme Marty, of whom “three patients complained of stomach aches before realizing that they were positive for Covid”.

His colleague Matthieu Calafiore tells us 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 caught this subvariant and not another.

Thai medical site

Above all, digestive problems have always been part of the possible symptoms of Covid-19, while remaining 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 were vomiting. These disorders were slightly more frequent in the case of infection with the Delta variant (respectively 6.6% and 8.9%).

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

So where did this claim come from that digestive disorders had become more frequent with this sub-variant? Many Internet users who often share information on the 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 hospital as well as genomic sequencing data from the UK, France and Australia show that the novel 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 details the profile of 14 positive cases, of which “almost all complained of severe abdominal pain”… without saying where it came from. Still, his conclusions were immediately taken up by many Internet users. Rémi Salomon also tells us that he based himself on different tweets. A certain Xabier Ostale, already known for having invented 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 switch of symptoms. I spent my time saying that we did not have enough data to affirm 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 assertions are not supported by evidence”, is moved by the German scientist Cornelius Roemer, regretting that “some viral tweets are getting out of control”.

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