CDC says it’s tracking new ‘mild but ultra-vaccine-resisitant’ BN.1 Covid variant

Health chiefs keep an eye on a new mild but vaccine-resistant strain of Covid as hospitalizations for the virus begin to recover.

The BN.1 variant is now behind one in 20 infections nationwide, estimates suggest, with numbers doubling about every two weeks.

By comparison, about a month ago, the strain was behind only one in 100 infections, estimates suggest.

The Centers for Disease Control and Prevention (CDC) has now added the variant to their watch list.

Its rapid emergence suggests it has an evolutionary advantage over the other circulating species.

Dr. Raj Rajnarayanan, a Covid expert at Arkansas State University, warned online that the new strain was “highly immune evasive.”

It is now the sixth most common in the country since arriving in September. The most common are BA.5 and its spin-off variants BQ.1.1. and BQ.1.

There is no evidence to date that BN.1 or any of the new subvariants are more likely to result in hospitalization or death.

While in the past there were only one or two dominant global variants, Covid now appears to have splintered into a swarm of closely related subvariants.

They are all derived from the Omicron strain that has sent global case numbers to record highs and all contain similar mutations.

Last month, scientists became concerned about a mutated strain – called XBB – that skyrocketed the number of cases in Singapore.

Weeks before, there were concerns about BA.275, the predecessor of BN.1 departing in South Asia. BQ1.1 started to take off in Europe before spreading to America.

It comes after U.S. hospital admissions jumped 3.5 percent in a week to 3,400 admissions per day. Cases and deaths remain flat. It is unlikely that the new BN.1 variant is behind the surge, as it is still spreading in relatively small numbers.

But the US healthcare system is simultaneously facing a “triple epidemic” of covid, flu and RSV as seasonal threats recover as virus control measures ease.

Several pediatric children’s hospitals are now at capacity across the country, while others have to set up tents to care for additional patients.

The updated bivalent boosters don’t target BN.1, but experts say they still need to improve protection by boosting the immune system.

Only 225 cases of BN.1 have been detected in the US so far, mostly in California, New York and Florida. 55 cases have been confirmed in the UK.

These are huge underestimates because not every positive Covid smear is analyzed for subvariants.

Since the strain emerged in late July, it has spread to 36 countries with 1,732 cases nationally, including the UK, France and India.

The CDC added BN.1 to its Covid variant dashboard on Monday.

It now makes up about 4.3 percent of infections nationwide, nearly double the 2.7 percent of two weeks ago.

At a meeting of the Infectious Diseases Society of America over the weekend, Dr. Natalie Thornburg, a microbiologist at the CDC, said cases of the strain could now double every two weeks.

“The uncertainty in that doubling time is a little bit higher because the absolute number of series is low, because the ratios are low,” she said.

Scientists warn it is likely better at evading immunity than others based on lab tests of its predecessor BA.2.75 – itself an evolved version of the original Omicron variant.

Modeling by the Bloom Lab at the Fred Hutchinson Cancer Center in Seattle, Washington, also cautioned that the new subvariant was likely better at escaping previous immunity — through vaccination or natural infection.

But there is no evidence at this stage that it is more likely to cause serious illness, hospitalization and death among those who contract it.

Bivalent vaccines are probably just as effective against this strain as others, but after studies suggested they were no better at tackling BA.4 or BA.5 – which they were designed for – and other variants.

Last month, the CDC also said it was monitoring the XBB strain — a fusion between BJ.1 and BA.2.75 variants — which it has called the “most vaccine-resistant ever.”

XBB caused a surge in Covid cases in Singapore, but it has failed to gain a foothold in other countries.

The species remains “very rare” in the US, scientists say — and has yet to be added to the CDC’s monitoring tool.

XBB is another spin-off of the Omicron variant and was blamed for the sudden wave of infections in Singapore.

The alarm was raised by experts, including Dr Rajnarayanan, who said it was the ‘most immune evasive yet’.

It comes after it was revealed that ten times more elderly Americans are being hospitalized with cold viruses than usual and tents have been set up outside hospitals as a result of the “triple epidemic” gripping the US.

Several children’s hospitals are already at or near record capacity for this time of year, and flu rates are the highest since the 2009 swine flu pandemic.

Experts say the “immunity gap” that emerged during lockdowns, work-from-home and mask mandates robbed Americans of significant exposure to germs that boost their immune systems.

The CDC reports that 7.4 of every 100,000 Americans age 65 or older have been hospitalized with a respiratory illness to date — numbers not normally seen until the dead of winter.

That figure is ten times higher than before the pandemic. But the rate is dwarfed by pediatric hospitalizations, with 50.6 of every 100,000 children age 17 or younger admitted for a respiratory bug this season.

The surge is driven by respiratory syncytial virus (RSV) and the flu – which are making a comeback this year after largely disappearing during the first two years of the COVID-19 pandemic.

RSV usually only causes mild colds in more people, but the virus can be especially harmful to young children. The CDC reports about 500 pediatric deaths each year.