Virologists and health officials worldwide are keeping an eye on a highly mutated form of the coronavirus that may be the most adept yet at slipping past the body’s immune defences, with some warning that it requires intense monitoring and vigilance many of its predecessors did not, writes MedicalBrief.
The mutated variant, BA.2.86, has been detected in Switzerland and in South Africa as well as in Israel, Denmark, the US and the UK, according to a leading WHO official.
The Omicron offshoot carries more than 35 mutations in key portions of the virus compared with XBB.1.5, the dominant variant through most of 2023 – a number about on par with the Omicron variant that caused record infections compared with its predecessor.
Reuters reports that it was first picked up in Denmark on 24 July after the sequencing of a virus had infected a patient at risk of becoming severely ill. It has since been detected in other symptomatic patients, in routine airport screening, and in wastewater samples in a handful of countries.
A dozen scientists worldwide said while it was important to monitor BA.2.86, it was unlikely to cause a devastating wave of severe disease and death, given immune defences built up worldwide from vaccination and previous infection.
The variant does not appear to make people sicker than earlier iterations of the virus; antiviral treatments should still work against it and tests should still detect it, according to a risk assessment last week from the US Centres for Disease Control & Prevention (CDC).
After igniting a global explosion of cases in the winter of 2021-2022, the highly contagious Omicron variant had spawned a slew of immune-evading descendants. Most fade into irrelevance.
Others, like the XBB lineage accounting for most US cases this year, outcompete the rest with their transmissibility and ability to infect – and reinfect.
Nearly every announcement of a new variant came with reassurance from public health officials that it did not cause more severe illness.
But BA.2.86 stands out in the Omicron family tree because of how much it has morphed. It has more than 30 mutations on its spike protein, the part of the virus that pierces through the cell and that vaccines train the body to fend off.
A number of experts believe the antibodies forged through battles with earlier variants will have a difficult time recognising this new foe.
“This is a radical change of the virus, like what happened with Omicron, which caught a lot of people defenceless,” Eric Topol, director of the Scripps Research Translational Institute, told The Washington Post.
“Even if they had a vaccine or prior infection, it could still get into them and infect them again or for the first time. We are facing that again.”
As of 24 August, there were about a dozen confirmed cases worldwide. This suggests international transmission is happening and far more cases are undetected.
What is unclear is whether the variant is transmissible enough to outcompete other variants and become the dominant strain, and the likelihood of it causing a surge. A variant adept at evading immunity would not take off in a population if it does not spread efficiently and multiply.
“We might either see this variant spread very widely, as happened with the original Omicron,” said Jesse Bloom, a computational biologist who monitors coronavirus variants at the Fred Hutchinson Cancer Centre in Seattle, “or it doesn’t end up spreading very widely and we continue to have these XBB variants.”
In one Swiss town, roughly 2% of coronavirus particles sequenced in a wastewater sample taken in early August were BA.2.86 variants. That was the first sign of a variant spreading within a community.
“Finding BA.2.86 in wastewater rather than in a patient is another piece of evidence that BA.2.86 is globally widespread by now,” said Tanja Stadler, a professor at the Swiss Federal Institute of Technology. “But it is still too early to tell if this variant will cause a major wave.”
When Omicron struck, huge swathes of the world lacked immunity because they never had Covid or had not been vaccinated – but that’s no longer the case.
“Most Americans, for instance, have antibodies to SARS-CoV-2 from vaccination, previous infection, or both, and it is probable that these antibodies will continue to provide some protection against severe disease from this variant,” the CDC said in its risk assessment of BA.2.86. “This is an area of ongoing scientific investigation.”
BA.2.86 poses a public health-messaging challenge. For a year and a half, headlines announced new Omicron subvariants with alphanumeric names that resemble pre-set WiFi passwords, accompanied by similar descriptions of immune evasion without causing severe illness.
Officials worry about a Covid-fatigued public tuning out news of a variant that could pose a serious threat. It’s only been a few weeks since another variant, EG.5, captivated public attention, even though it’s not all that different from its XBB cousin.
The rise of BA.2.86 has raised concerns about declining visibility into the evolution of the virus. Genetic sequencing is necessary to track variants but these efforts have been pared back globally.
GISAID, a global data-sharing initiative for the coronavirus, has seen specimens collected for genetic sequencing plunge from 425 000 in August 2022 to 38 000 last month.
“It is still low numbers,” said Maria van Kerkhove, Covid-19 technical lead at the WHO, of BA.2.86.
That the known cases are not linked suggests it is already circulating more widely, particularly given reduced surveillance worldwide, she said.
Scientists are testing how well updated Covid-19 vaccines will work against BA.2.86, and Kerkhove said these had been better at preventing severe illness and death than reinfection.
Risk assessment
“We are in a very different phase (of the pandemic) than if this popped up in the first year,” said Marion Koopmans, a Dutch virologist who advises the WHO.
Nirav Shah, principal deputy director of the CDC, said it appeared that current tests and medications remain effective against BA.2.86, though the variant may be more capable of causing infection in vaccinated people and those who have had Covid-19 previously. Shah confirmed there is no evidence yet that it is causing more severe illness.
Still, the potential risk must be taken seriously, experts said, and surveillance must continue, if not at levels undertaken at the pandemic’s peak.
“Governments cannot drop the ball,” Van Kerkhove said, adding that the coronavirus continues to circulate, evolve, infect and kill people.
How much surveillance is needed to track the virus remains an open question, health experts said, and the countries that have detected the new variant all have strong genomic sequencing capacity.
By 2022, 84% of countries could sequence Sars-CoV-2 in-country, according to WHO figures.
Hospital admissions
“When we do sequencing now, it is like (finding) a needle in a haystack,” said Tyra Grove Krause, a Danish epidemiologist at the Statens Serum Insitut, which identified three BA.2.86 cases.
The WHO said Covid-19 testing has declined 90% worldwide from the peak. Testing has also plummeted in the US, and sequencing is down by about 90%, said Ashish Jha, who served as White House Covid-19 response co-ordinator until June.
Data from hospital admissions, emergency room visits, deaths, wastewater sampling and sequencing, including at airports, have helped fill in the global picture, he said.
Jha and others, including the European public health agency and Covax, the global programme for getting vaccines to the world’s poorest, said Covid-19 surveillance and defences could be reactivated in the event of a major infection wave.
“It would take resources; it would take will; it would take people deciding this is important to do,” Jha said. “But we have largely figured out how.”
Regardless of whether BA.2.86 becomes a threat, Topol, Scripps Institute director, said the potential mismatch underscores the folly of attempting to annually update vaccines for an ever-evolving virus.
He said government officials should steer resources toward developing vaccines that are essentially variant-proof, with the ability to target a broad range of coronaviruses.
For now, experts say the rise of BA.2.86 is more of a subject for scientific scrutiny than public panic.
See more from MedicalBrief archives:
Another new Covid variant alert
UK spike in new Covid variant cases
First SA case of Covid’s EG.5 variant