New versions of the Omicron variant make gains against BA.2

by Brenda Goodman, CNN

Arguably the most successful version of the Omicron coronavirus variant to date is BA.2 – but it hasn’t rested on its laurels.

BA.2 picked up mutations, sometimes transitioning into sleeker and, incredibly, even faster versions of itself.

Global variant trackers have found 21 viral progeny associated with BA.2. Most of them look like underachievers, with inconsequential mutations. But two of those offshoots — BA.2.12.1 and BA.2.12 — have fueled an increase in Covid-19 cases and hospitalizations in central New York state. And one of them, BA.2.12.1, also exceeds BA.2 in other regions.

New data from the US Centers for Disease Control and Prevention estimates that BA.2.12.1 caused 19% of new Covid-19 infections in the US last week, up from around 11% of cases the previous week and 7% the week before that.

The rate at which BA.2.12.1 overtakes BA.2 is about as fast as BA.2 outranked its cousin BA.1according to Trevor Bedford, an epidemiologist and genomics scientist at the School of Public Health at the University of Washington.

Although BA.2 is still very present, it has lost ground. Last week, it caused about 74% of Covid-19 cases, according to CDC data, up from nearly 76% the previous week.

Together, BA.2 and BA.2.12.1 accounted for about 93% of new Covid-19 cases in the United States last week.

“BA.2.12.1 has increased rapidly in proportion in the United States relative to other BA.2 sublineages,” particularly in the region that includes New York and New Jersey, the CDC spokeswoman said, Kristen Nordlund, in an email.

New sub-lines emerge

Last week, the New York State Department of Health alerted residents to the new sublines, warning that they were spreading about 25% faster than BA.2 and causing an increase in Covid cases. -19 and hospitalizations, especially in the central part of the state. . He urged New Yorkers to “act quickly” to consider wearing masks, to get booster doses of vaccine, to get tested if they have symptoms and to seek treatment if they are infected.

Officials are concerned about the ramifications of BA.2 because they swapped pieces of their spike proteins at key locations called L452Q and S704L.

Virologists have seen mutations in these positions before. The Delta variant had a switch at 452, which helped the virus bind more tightly to the ACE2 receptors on our cells.

“And these mutations allow the virus to enter cells faster and also help evade antibody responses generated by vaccination or infection,” said Andy Pekosz of the Johns Hopkins Bloomberg School of Public Health.

“What we really don’t know at this time is to what extent these mutations will contribute to increased spread or increased severity of the disease,” he said. “It’s something that’s going to take us some time to figure out.”

Pekosz says he and others are working on it right now.

The fact that cases are increasing in New York is also a bit concerning. This means that these viruses are good at bypassing our immune defenses.

“The vast majority of New Yorkers have either been vaccinated, infected, or both. And so what we’re seeing are reinfections. We see this immune evasion,” said Dr. Daniel Griffin, a physician and researcher at Columbia University Medical Center.

Two other Omicron sub-variants, BA.4 and BA.5, have started circulating at low levels in other parts of the world, including South Africa, Botswana, Germany and Denmark. They also have mutations at 452, among others.

“I think it’s interesting that we’re getting into a different kind of evolutionary regime for SARS-CoV-2, in that the virus is able to pick up mutations that are more transmissible, at least we have it seen three times now with Omicron. So I think from a scientific perspective, it’s interesting,” said Shishi Luo, associate director of bioinformatics and infectious diseases at Helix, a company that tracks coronavirus variants.

Will the new sublines affect public health?

What this might mean for public health is still an open question. Luo says it’s too early to know how well current Covid-19 vaccines defend against subvariants, but she’s hopeful that because they’re linked to BA.2, protection against severe consequences like the hospitalization and death will hold.

She notes that experts have not seen new subvariants increase Covid-19 hospitalizations in countries like South Africa. So she hopes that even if cases start to rise here, hospitalizations will continue to stay low.

If you’ve been vaccinated or previously infected — if your immune system has already seen and recognized some of the virus — and you catch Covid again, your chances of going to hospital are reduced by about 90%, Griffin says. . If you test positive quickly enough and you receive treatment, such as monoclonal antibodies or Paxlovid, that’s another 90% reduction in the likelihood of you ending up in hospital.

“If we do everything right from now on, we shouldn’t see a lot of people ending up in the hospital,” Griffin said.

He points out that contracting the Covid is still not without risk. He sometimes sees people who ended up with long Covid after being vaccinated and boosted.

“It’s just a gamble. As long as people are infected, you still have a chance of doing so despite vaccines,” Griffin said.

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