What We Know About 'IHU' COVID Variant B.1.640.2 With 46 Mutations

A coronavirus variant has been identified in France and named B.1.640.2—but it's too early to say much about it based on the low number of known cases.

The variant was outlined in a study released December 29 after twelve cases were identified in southeastern France late last year after one patient had returned from Cameroon.

That patient, a male, had developed mild symptoms a day before his diagnosis in mid-November 2021. Testing showed an "atypical" combination of spike genome mutations that did not correspond to the pattern seen in the Delta variant at that time.

Genome sequencing was carried out at the university hospital institute Méditerranée Infection, and revealed some mutations similar to those seen in other variants including Omicron. Analysis of the variant revealed 46 mutations along with 37 deletions to its genome.

The report describing the variant has not yet been peer-reviewed, meaning that it has not yet been rigorously evaluated by other scientists, so findings should be taken with caution. It was released on the medRxiv pre-print repository.

It should also be noted that the variant is not that new. The first sequence was uploaded to the GISAID COVID sequence database on November 4, nearly three weeks before the first Omicron sequence was uploaded, Tom Peacock, a virologist at Imperial College London, tweeted on Monday.

In addition, it wasn't until early December that proposals were made to split B.1.640.2 away from its older parent lineage B.1.640 due to the emergence of new mutations.

B.1.640 itself was identified in September and placed under monitoring by the European Centres for Disease Prevention and Control (ECDC), but has not yet been elevated to a higher level of concern. At least one news report on this variant has claimed it is more infectious than Omicron, but it's not clear whether this is really the case.

The December 29 study states it is not yet possible to say much at all about how fast B.1.640.2 spreads or what sort of illness it might cause.

It read: "It is too early to speculate on virological, epidemiological or clinical features of this IHU variant based on these 12 cases."

A number of scientists have dismissed concerns about B.1.640.2—also dubbed the "IHU" variant in the December 29 study—at this stage.

Peacock described the variant as "definitely not one worth worrying about too much at the moment," noting a relatively low number of sequences identified—roughly 20 as of Monday—compared to Omicron.

Meanwhile, Francois Balloux, director of the genetics institute at University College London, tweeted on Monday that B.1.640.2 "has not sent hundreds of people [to the] ICU in France" and advised people to "please relax for now."

Omicron, for contrast, continues to drive a surge in U.S. coronavirus cases, with Johns Hopkins University data suggesting the country reported more than one million new cases in a single day on Monday—a global record.

A scientist in a laboratory looks at a sample through a microscope. Scientists identified a COVID variant late last year but say it's too early to say much about it due to limited cases. Niphon Khiawprommas/Getty