A new Covid variant responsible for a resurgence in hospital admissions could be deadlier than previously thought, research suggests.
BA.2.86 – or 'Pirola' – is a mutation on the Omicron BA.2 subvariant and is the ancestor of the currently dominant JN.1, which as of January 6 is responsible for more than three in five Covid cases.
Both have about 60 more spike protein mutations than the original coronavirus and over 30 more than other Omicron variants such as BA.2 and XBB.1.5.
A study from Ohio State University found that BA.2.86 can infect cells in the lower lungs and penetrate cell membranes more efficiently than other versions of Omicron.
Dr. Shan-Lu Liu, senior author of the study and professor of virology at Ohio State University, said the findings were “concerning.”
“The concern is whether or not this variant, as well as its descendants, including JN.1, will have an increased propensity to infect human lung epithelial cells, similar to the parent virus that caused the 2020 pandemic,” he said.
Researchers at Ohio State University found that BA.2.86 can infect human cells that line the lower lung and penetrate cell membranes more efficiently
In the week ending December 30, 2023, there were 34,798 Covid hospitalizations in the US, up from 28,893 the previous week
JN.1, derived from BA.2.86, now accounts for almost two-thirds of Covid cases
In laboratory tests, the researchers found that BA.2.86 was more efficient at infecting people in the lower lungs.
This means it is more likely to cause serious illness than other Omicron variants, as symptoms arising from the lower lungs are seen in more severe cases. They may include chronic coughing and breathing difficulties, which may indicate pneumonia.
Infection of lower lung cells is made easier by a cell surface protein called TMPRSS2, which promotes the joining of the virus cells and lung cells and is a known contributor to Covid infection and symptoms in the respiratory tract.
The researchers wrote: 'BA.2.86 may have an increased propensity to use the plasma membrane route of entry, as opposed to the endosomal route of entry.'
This means that BA.2.86 enters cells more efficiently by directly penetrating the cell membrane instead of attaching to the cell surface and collecting receptors.
The experiments were carried out with pseudoviruses – a non-infectious part of a virus surrounded by several Covid spike proteins on its surface that are structured to match known variants.
“We need to confirm these findings using the real virus,” Dr. Liu said.
'But from our past experiences we know that infectivity in human epithelial cell lines provides very important information.'
He added: 'That raises potential concerns about whether or not this virus is more pathogenic compared to recent omicron variants.'
Although laboratory tests have shown that BA.2.86 is more severe, this is not reflected in official data.
BA.2.86 began circulating in America in August 2023.
Since then, deaths from Covid-19 have remained very low. In the last week of 2023, the CDC estimated there were 839 deaths from the virus.
Counties in Montana, Colorado, West Virginia and Nebraska are among those with current Covid hospitalization rates above 20 per 10,000 residents
In the last week of 2022, there were 3,658 deaths from Covid.
Hospitalizations have increased since BA.2.86 arrived on the scene in August 2023. There were 20,699 Covid hospitalizations in America in the first week of September, up from 6,487 in the first week of July.
However, the number of hospital admissions is still much lower than last year.
There were 34,798 Covid hospitalizations in the US in the week ending December 30, compared to 44,542 in December 2022.
And in January 2022, at the height of the pandemic, there were 150,650 deaths in one week.
The Ohio State researchers also found that the bivalent booster vaccine effectively neutralizes BA.2.86, which would explain why the variant did not cause a huge surge as previously feared.
In a separate experiment, researchers analyzed antibodies in blood samples from healthcare professionals who had received three monovalent Covid vaccines, two monovalent vaccines and one bivalent booster, and first responders who had had Covid during the XBB.1.5 wave.
They compared the ability of antibodies to block infection by BA.2.86, the original Covid virus, an XBB-derived variant known as FLip, and several Omicron variants.
The Ohio State researchers found that booster dosed antibodies from health care workers' antibodies were more efficient at neutralizing BA.2.86 than they were when neutralizing other omicron variants, including XBB.1.5.
In contrast, the three monovalent vaccines and previous XBB.1.5 infection were barely effective in blocking infection by BA.2.86.
The research was published in the journal Cell.
