IHU Covid-19 Variant Explained

While IHU has almost as many mutations as Omicron, there is no evidence so far that it is more transmissible, dangerous, or better able to evade vaccines than other variants.

In December 2021, a preprint study published in medRxiv described a new coronavirus variant known as IHU, or B.1.640.2 (A preprint is a study that has not yet been certified through peer-review and medRxiv warns that the studies it carries should "not be relied on to guide clinical practice […] and should not be reported in news media as established information".)

Like most COVID-19 variants, the identity of a new variant kicked off widespread conversation about the threat of yet another variant.

According to the Centers for Disease Control and Prevention (CDC), novel coronavirus variants crop up all the time. That's because SARS-CoV-2, the virus that causes COVID-19, is constantly changing and accumulating mutations in its genetic code over time.

Some, like the highly transmissible Omicron variant, emerge and continue to spread, replacing previous variants. While most variants will emerge and disappear. The IHU variant appears to have taken the latter path as it does not appear on the CDC's model of circulating variants, Nowcast.

Nor is it a variant of concern according to the the World Health Organization (WHO). The WHO did not designate IHU as either a variant of interest or a variant of concern—two categories the organization uses to monitor variants that pose a threat.

While the variant made news to the wider public in late 2021/early 2022, officials actually knew about it for a little bit longer. In January 2022, Abdi Mahmud, a COVID incident manager with the WHO, told reporters in a press briefing that IHU has been on the agency's radar since November 2021, but that the variant doesn't appear to have spread widely over the past two months, per reporting from the New York Times.

Even though IHU doesn't appear to have picked up or started circulating beyond France, many are curious about the variant anyway—here's what we know.

IHU COVID Variant

What Is the IHU Variant?

According to the medRxiv preprint study, the IHU variant was first detected in a sample from France collected during mid-November of 2021, around the same time Omicron was first discovered. The sample came from a vaccinated adult who lived in a small town in Southeastern France and had recently returned from Cameroon, Africa.

The patient exhibited mild respiratory symptoms. In total, researchers identified 12 cases of the variant, all from the same area of France.

Because the pre-print study was written by researchers from Méditerranée Infection University Hospital in Marseilles, France, the virus was named IHU, after the shortened name of the hospital.

After analyzing the 12 samples, researchers found IHU has 46 mutations and 37 deletions. Each of these mutations and deletions refers to a single change in the virus' genetic code. Each change could potentially alter characteristics of the virus, like how transmissible it is, according to the Centers of Disease Control and Prevention (CDC).

What piqued researchers' attention the most was that 23 of these mutations and deletions were on the spike protein, aka the part of the virus that penetrates cells and causes infection. (For comparison, Omicron has 50 mutations, 30 of which are on the spike protein.)

The spike protein is also the area of the virus COVID vaccines are designed to target, Gregory Poland, MD, founder and director of the Mayo Clinic Vaccine Research Group and editor-in-chief of the journal Vaccine, told Health.

Current vaccines are formulated to recognize and disarm the original strain of COVID-19's spike protein. In contrast, Omicron—and potentially IHU—have spike proteins that look quite different, said Dr. Poland.

It's kind of like comparing a pencil to a highlighter: while both are writing instruments, each has its own unique appearance. So if you have a vaccine that's trained to spot pencils, it won't be as good at spotting highlighters, meaning some slip through its radar.

Additionally, two of IHU's spike protein mutations—N501Y and E484K—have been associated with increased transmissibility in other variants, like Gamma, Judith O'Donnell, MD, section chief of infectious diseases at the Penn Presbyterian Medical Center in Philadelphia, told Health.

However, IHU has many other mutations, and it's not yet clear how all these mutations interact with each other to change how the virus operates, Dr. Poland says. Therefore, it's too early to tell whether IHU is more transmissible, better able to evade vaccines, or more likely to cause severe symptoms.

Should We Be Concerned About the IHU Variant?

So far, IHU is very rare: Only 20 samples of the variant have been detected, sequenced, and uploaded to the GISAID database (a public database for tracking COVID-19), Mark Adams, PhD, the deputy director of the Jackson Laboratory for Genomic Medicine, a research facility in Farmington, Connecticut, that tests COVID-19 samples, told Health. In contrast, over 120,000 Omicron sequences have been uploaded since mid-November, suggesting that IHU is not more transmissible when compared to Omicron.

"Based on the timing of when the variant was identified in early November, and then the subsequent of Omicron in France in December, this new variant appears not to be as concerning," said Dr. O'Donnell. "Omicron outcompeted [IHU] very easily in France, and there have been no additional cases of infection with IHU reported in France, or in other areas of the world."

Even so, Dr. Poland said it's too soon for researchers to write off IHU completely. "Part of the problem is a relative lack of genetic sequencing," he pointed out, noting that more than 20 people have certainly been infected with IHU—they just haven't been identified. "We don't know how far IHU has spread or how transmissible it is. That answer will likely emerge in the next week or two."

Why Do Viruses Mutate?

All viruses, including SARS-CoV-2 (the virus that causes COVID-19), change over time, according to the WHO. Certain viruses—like HIV, influenza, or SARS-CoV-2—mutate faster than others, said Dr. Poland.

Here's why: Every time a virus infects a cell, it makes a copy of itself. While some viruses have DNA proofreaders that scan for and fix errors, SARS-CoV-2 does not. This means each time it replicates in a new host, errors could occur—kind of like typing on your computer without being able to look at the screen, said Dr. Poland.

Most of these typos—aka, mutations—won't affect how the virus acts, according to the WHO. But some may affect how easily it spreads; how deadly it is; or how good it is at evading vaccines, medicines, or diagnostic tools.

"It is not at all surprising that there is another COVID-19 variant, and others will emerge over time," said Dr. Adams. "However, it's difficult to predict when new variants will occur, where each variant will arise, or what the characteristics of that variant will be."

That's why robust genetic sequencing programs are so important; they help researchers spot and react to new, potentially dangerous changes in a virus, said Dr. Adams.

This is also why it's crucial that people around the globe work together to curb the spread of COVID-19, either through widespread vaccination or public health measures like social distancing and masking, according to the WHO. These measures reduce opportunities for the virus to mutate and form a new variant.

"Every time you give the virus the opportunity to infect the next human, it's like handing it a lottery ticket. Anything could happen," said Dr. Poland.

The Bottom Line: Don't Lose Sleep Over IHU

At the end of the day, IHU is not something you should be worried about, at least right now. Instead, Adams says there are two much more concerning COVID-19 variants that people should focus their efforts on: Omicron and Delta.

According to the CDC, the best ways to protect yourself and your community from these variants giving you COVID-19 include:

  • Getting vaccinated: Everyone 5 years and older should get fully vaccinated, which will prevent severe illness, hospitalizations, and death.
  • Obtaining your booster if you're eligible.
  • Wearing a mask, particularly indoors in public settings where there is high community transmission (aka, most of the country).
  • Testing yourself, if you develop symptoms of COVID-19, like a fever, headache, cough, or sore throat.

Bottom line: "Let the epidemiologists worry about IHU," said Dr. Poland. "There are hundreds of variants that you don't even know about. You're only hearing about this one because it was reported."

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