WHO adds BA.2.86 to SARS-CoV-2 variant monitoring list

SARS-CoV-2 sequencing

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The World Health Organization (WHO) SARS-CoV-2 virus evolution advisory group today added BA.2.86 as a variant under monitoring (VUM) due to its many mutations, which follows recent detections in Israel and Denmark, and now today with a report of a sequence from Michigan.

Meanwhile, health officials are closely watching EG.5, which the WHO added as a VUM on July 19 and elevated to a variant of interest (VOI) on August 9. Today, the European Centre for Disease Prevention and Control (ECDC) added EG.5 and other viruses that carry the F456L mutation as VOIs because of rising transmission in some European countries and in other world regions.

WHO urges ramped-up sequencing

Earlier this week, virologists in Israel and then Denmark on social media reported a few sequences that appear to be second-generation Omicron BA.2 variants, tentatively called BA.X, with large numbers of mutations, especially on the spike protein.

Given the global decline in sequencing, they said the detection in two different regions suggests that the virus may be circulating more widely. Also, they noted that the existence of many mutations raises questions about a wide range of outcomes.

The WHO said the earliest documented sample is from July 24.

In announcing the VUM addition today, Maria Van Kerkhove, PhD, the WHO's technical lead for COVID-19, on Twitter said there is very limited information available now, but the large number of mutations needs closer monitoring. "Surveillance, sequencing, and COVID-19 reporting [are] critical to track known and detect new variants," she said, repeating that COVID-19 is still here, and as the virus continues to evolve, more variants will emerge.

Today, virologist Nick Rose on Twitter said a sequence from Michigan collected on August 3 has been uploaded to a sequencing database. The sequence marks the fourth known BA.2.86 detection.

Ryan Hisner, a science teacher who is active in the variant tracking community, said on Twitter it's too early to forecast what impact BA.2.86 will have, but with early indications of wide geographic spread, it doesn't seem likely to disappear quickly.

Denmark's Statens Serum Institute said yesterday that neither of the country's two BA.2.86 case-patients were immunocompromised and have no epidemiologic links. It added that so far, there's no sign that the variant causes severe disease. Today, SSI said it is culturing the virus to provide further characterization.

ECDC steps up virus monitoring for F456L mutation

In a statement today, the ECDC said COVID transmission is increasing in some European countries alongside increasing detections of viruses related to XBB.1.5 that carry the F456L mutation in the spike protein. EG.5 is the most prevalent virus carrying F456L, but the ECDC said other lineages under the XBB.1.5 umbrella also carry it, including FE.1, which became dominant in Brazil but didn't spread widely across the globe.

The agency said viruses with the spike protein change have an elevated growth rate, including in the United States, the United Kingdom, and elsewhere in Europe, probably due to the change itself. Another lineage with the change showing a growth advantage is FL.1.5.1, which is dominant in the Dominican Republic and is circulating elsewhere. Others include XBB.1.16.6 and XBB.1.5.59

There is currently no sign of increased hospitalisations or pressures on healthcare systems.

The ECDC said the growth rate advantage is likely caused by increased immune escape, along with waning population immunity. It emphasized, however, that other drivers could be fueling increased transmission rates, including large gatherings during seasonal holidays. "There is currently no sign of increased hospitalisations or pressures on healthcare systems," it said.

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