ECDC details rising COVID-19 as more Asian nations report BA.2.86

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COVID indicators are rising in Europe from very low levels, likely due to multiple factors, the European Centre for Disease Prevention and Control (ECDC) said today in an epidemiological report, adding the caveat that current data are limited, owing to reduced resting and reporting.

In other developments, Japan and South Korea reported their first highly mutated BA.2.86 sequences, as other countries uploaded more sequences to databases.

Mutations make COVID circulation unpredictable

Data from 24 countries show a rise in the 14-day case rate, with growth very limited and at a far lower magnitude than other epidemic peaks, the ECDC said. Countries reporting age-specific data show increased case rates in people ages 65 and older, a group known to be at higher risk for severe disease. Meanwhile, test positivity was up in 12 of 19 reporting countries.

Hospitalization and intensive care unit admission levels were stable, but a few countries reported a rise in death rates from COVID, especially among older people.

Large gatherings and increased travel during summer holidays might increase COVID transmission, and after several months of low transmission, protection against infection—but not severe disease—is probably waning, the ECDC said. It added that so far, virus activity hasn't settled into a seasonal pattern, given that SARS-CoV-2 can acquire mutations that keep it circulating at unpredictable times of the year.

The increase in activity comes amid rising global proportion of XBB variants carrying the F456L mutation, which gives variants such as EG.5.1 a selective advantage. The ECDC added, however, that there is no evidence that XBB viruses with the F456L mutation have characteristics that would elevate it from a variant under monitoring to a variant of concern.

Regarding BA.2.86, the ECDC said unpublished phylodynamic analysis suggests it emerged recently, between May and July, and may be linked to a higher growth rate, given its detection in several countries in people with no known epidemiologic links. The ECDC said it's too early to tell how well the heavily mutated virus will compete against more recent XBB variants. It added that recent pseudovirus neutralization lab studies suggest that hybrid immunity, especially in people who had a booster dose and were sick with an XBB variant, offers some protection against BA.2.86.

So far, it's unlikely that BA.2.86 will lead to more severe disease or reduce vaccine effectiveness against severe disease, the ECDC said.

"However, older individuals and those with underlying health conditions remain at an increased risk of severe disease if infected," said ECDC Director Andrea Ammon, MD, MPH in a press release, "so autumn vaccination programmes should prioritise protecting individuals at risk of severe disease, such as those aged over 60 years and other vulnerable groups."

More countries report BA.2.86 sequences

In other BA.2.86 developments, Japan and South Korea are among the countries to upload their first sequences to databases, according to scientists tracking the variants. Elsewhere in Asia, Hong Kong's Centre for Health Protection today said wastewater surveillance turned up BA.2.86 in 1 of 24 samples.

In Japan, the Sato lab based at the University of Tokyo today became the fourth to assess BA.2.86 neutralization, which hints that BA.2.86 is more transmissible than XBB.1.5 and is comparable to or greater than EG.5.1. The pseudovirus experiments suggested that BA.2.86 is less infectious than EG.5.1. Unlike with the other three studies, different types of vaccine sera tested, including the bivalent version that included BA.5, found no neutralization activity against BA.2.86, nor against EG.5.1.

In the United States, a sample was uploaded from Washington, raising the number of states reporting samples to six.

And finally, researchers from Denmark today reported on the country's first 10 cases involving BA.2.86, which were reported from July 26 to August 21. Writing in Eurosurveillance, they said 9 of the patients were tested based on clinical indications, and 1 was tested as part of a workplace surveillance project.

Some of the patients belonged to the same household, but most had no epidemiologic or geographic links. Most had no relevant travel history. Symptoms were similar to other variants, mainly cough, shortness of breath, and fever. Some had underlying conditions or were on immune-modulating treatment. None of the patients experienced severe illness.

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