What to Know About the HV.1 Variant

Yet again, there's a new COVID variant on the scene, but experts say there's no cause for concern.

For the 2-week period ending October 14, the CDC projects that the HV.1 variant will account for nearly 20% of cases. Only the EG.5 variant makes up a larger proportion of cases, estimated at 24%.

HV.1 jumped from an estimated prevalence of about 13% for the 2-week period ending September 30, according to CDC's variant proportions tracker. For the finalized reporting period just prior to that, HV.1 accounted for about 8% of cases.

Shishi Luo, PhD, head of infectious diseases at the population genomics company Helix, which sequences SARS-CoV-2 in samples from both outpatients and hospitalized patients, said HV.1 hasn't raised any red flags yet.

The prevalence of HV.1 "in hospitalized patients is similar to the prevalence in non-hospitalized patients," Luo told MedPage Today, noting that the same is true for EG.5 and FL.1.5.1, estimated to be the third-most prevalent variant at this time.

"We're treating it as any other new variant, monitoring it and looking for signs that it will lead to more severe disease, or if it's more transmissible, so that healthcare workers can be prepared," Luo said.

Researchers are at something of a different place with new variants these days, Luo said. "Rather than trying to follow what the new mutations are and seeing if neutralization assays or experiments are done to investigate the functional impact of the mutation," she said, more experts are "waiting to see if there's an increase in prevalence of a particular variant in hospitalizations," adding that those are the real-world data supporting that there is greater severity.

"It's hard to extrapolate experimental data to what's going to happen" in the real world, she noted.

Indeed, in August, the CDC issued a risk assessment about the BA.2.86 variant, which was dubbed "Pirola" by the media. It raised alarms because it had more than 30 novel mutations, and CDC's assessment was that it "may be more capable of causing infection" in those who'd been vaccinated or previously had COVID.

Yet it never ended up increasing in frequency, even though it was "detected sporadically in the U.S.," Luo said.

The story is a bit different in Europe, where BA.2.86 accounts for about 10% of cases in Denmark, "where most of the first cases were detected." However, at below 1% of cases in the U.S., it "won't be reported by CDC's variant tracker," she said.

Luo noted that HV.1 is a sublineage of XBB.1.9.2, so it is still within the Omicron family. It's actually a direct descendant of EG.5, according to CDC's lineage tree.

Luo reiterated the importance of continued surveillance for new COVID variants -- as well as for other respiratory pathogens including influenza and respiratory syncytial virus (RSV).

"We should monitor all of the respiratory viruses in the same way we currently monitor COVID, and that should help with hospital preparedness and resourcing," she said. "We should take the lessons we learned from COVID and apply them to make our future situation better.

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