A potentially faster-spreading COVID Delta-plus variant, AY.4.2, has been spotted in 8 states


Laboratories in at least 8 states have detected a potentially faster spreading “sub-strain” of the delta variant of the coronavirus called AY.4.2, and UK health authorities say they are investigating an increasing proportion of cases of this strain of the virus.

Labs in California, Florida, Maryland, Massachusetts, Nevada, North Carolina, Rhode Island and Washington State, as well as the District of Columbia, have so far detected at least one case of AY.4.2.

While it may spread somewhat faster, health authorities have found no evidence of a more serious illness caused by the variant, they say. Current Vaccines remain effective against it.


The sub-descent has remained a small fraction of the cases circulating in the United States for several weeks, but US health officials say they are already stepping up efforts to study the descendant of the new delta variant.

“We have teams that are constantly reviewing genetic sequence data and looking for light signals, a certain percentage increase or just something completely new,” says Dr. Summer Galloway, executive secretary of the US government’s SARS-CoV-2 Interagency Group. .


Galloway, who also serves as a policy leader on the Centers for Disease Control and Prevention’s Laboratory and Testing Task Force, said US labs began preparing last month to prioritize tests to assess whether AY.4.2 could evade antibodies from vaccinated Americans, or from currently authorized monoclonal antibody treatments for the virus. .

This process can take up to four weeks, Galloway said, across many laboratories that will run tests with harmless “pseudoviruses” designed to impersonate the variant’s characteristic mutations.

Scientists have already revealed alarming combinations of mutations in other delta subspecies called AY.1 and AY.2, which like AY.4.2 have sometimes been named interchangeably.Delta Plusvariables.

Last month, the Biden administration temporarily suspended distribution of a Monoclonal antibody therapy In Hawaii after the estimated cases of AY.1 rose to 7.7% in the state. The Food and Drug Administration said laboratory trials of AY.1 indicate that it is “unlikely” that the drug will be effective against the alternative.

The state has since resumed use of antibody therapy, after AY.1 dropped below 5% in Hawaii. Nationwide, AY.1 hovers around 0.1% of cases.

“Right now, I think there’s not a lot that we know. But in terms of the public health risk it poses, the prevalence is very low in the United States and we don’t really expect that the alternatives [of AY.4.2] It will have a significant impact on the efficacy or amenability of our vaccines for monoclonal antibody therapies.”

In the UK, AY.4.2 rose to more than 11% of delta variant cases. Health officials there say the alternative does not appear to have led to a “significant decrease” in the effectiveness of the vaccine or an increase in hospitalizations, but can be It spreads faster due to a ‘slight increase in biological transmission’.

“Estimated growth rates remain slightly higher for AY.4.2 than deltas, and the rate of home secondary attacks is higher for AY.4.2 cases than for other deltas,” said a report published by Britain’s Health Security Agency on Friday.

The Centers for Disease Control and Prevention estimates that AY.4.2 made up less than 0.05% of cases circulating in the United States for several weeks, according to an agency spokesperson. Taken together, the CDC estimates that delta variable Its subspecies have been nearly 100% of cases in the United States for months.

“Even based on the data in the UK, if you look at the cast feature, it looks smaller. It’s not like the delta, which once it came out, was roughly 50[%] Dr. Karthik Gangavaraphu, a postdoctoral researcher in the UCLA Suchard Group, says he has a 60% lead over all previous strains.

Gangavarapu was part of the team that led the various tracking efforts of Scripps research at Outbreak.info, which tracked variants like AY.4.2 as they appeared in an international database of “sequenced” viruses maintained by a group called the GISAID Initiative.

“It can have a slight transmission advantage, but it can also have other important factors. For example, how is the immunity of a population in a particular site? What is the vaccination rate? It might have some sort of influence on how that changes,” Gangavarapu said.

The largest share of the virus circulating in the United States is still closely related to the original delta variant, among the samples reported to GISAID. Scientists have speculated that the next major type of concern could emerge as a mutation of the delta variant, though Gangavarapu cautioned that the highly contagious strains arose independently of each other.

Delta variant subspecies such as AY.25, AY.3 and AY.44 also currently account for significant proportions of cases in the United States, but not necessarily because they have an advantage over their siblings.

Outbreak.info previously counted AY.4.2 views in at least 35 states. However, Gangavaraphu said a flaw in the pangolin system used to generate reports of variants resulted in some false positives for the sub-breed showing up in some numbers.

Scientists often reclassify new substrains to “help researchers track the virus” that cluster in certain regions, even when they have mutations that don’t have a measurable impact on a variant’s public health risk.

“We’ll probably get more data over the next month or so to see if there’s been the same kind of increase in prevalence that we’re seeing in the UK in the US so far,” says Gangavarapu.



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