A new omicron subvariant called BA.2.86 has been detected in several countries including the United States. This highly mutated strain is raising concern among public health officials, who are closely monitoring its spread and properties.
BA.2.86 appears to have descended from the BA.2 omicron lineage that caused case surges in early 2022. But it contains over 30 additional mutations compared to BA.2 and other recent omicron subvariants.
The World Health Organization has designated BA.2.86 as a “variant under monitoring”, its second highest tier for variants of concern. This designation reflects the large number of changes seen in BA.2.86 and the potential for immune evasion.
So far only 11 cases of BA.2.86 infection have been sequenced worldwide. These came from the US, Israel, Denmark, UK and South Africa. The strain has also been detected in US wastewater samples, indicating it is transmitting stealthily.
Experts say the mutations in BA.2.86’s spike protein likely enable it to bypass immunity from vaccination and prior infection. But it remains unclear whether the variant causes more severe illness or is significantly more transmissible than other circulating strains.
Too Soon to Predict Spread and Impact
Some scientists have speculated BA.2.86 (Pirola) may trigger a new wave of infections. But experts emphasize there is no evidence for that yet.
“It’s impossible to gauge anything about transmissibility or disease severity from that small number of cases,” says Andrew Pekosz, a Johns Hopkins University virologist.
For BA.2.86(Pirola) to succeed against competing variants, it would need high inherent contagiousness like XBB, BQ.1 and other omicron strains currently dominating many regions.
At this stage, it’s unlikely BA.2.86 is fueling the rise in US cases and hospitalizations in recent weeks. Those are more likely driven by subvariants like BQ.1 and XBB’s descendant EG.5.
The CDC says there is currently no sign BA.2.86 causes more severe illness than other variants. But more data is needed as cases accumulate to clarify the new variant’s properties.
Monitoring Closely for Signs of Spread
Experts emphasize the need to aggressively track BA.2.86’s prevalence relative to other circulating strains. Within weeks, genetic surveillance should indicate if it is gaining ground or fizzling out.
“The variant is probably spreading much more broadly than we’ve detected so far,” says Pekosz, due to limited sequencing globally.
The CDC is carefully watching BA.2.86’s mutations and potential to escape immunity, which could theoretically spark a new wave. But right now it remains a tiny fraction of overall cases compared to dominant strains like BQ.1 and EG.5.
Continued genomic sequencing and data sharing worldwide remain essential to identify and characterize new concerning variants like BA.2.86 early while case numbers are still low.
Implications for Fall Boosters
BA.2.86’s numerous spike mutations suggest COVID vaccines updated against BA.5 and XBB may have low effectiveness against it.
“The reactivity of the booster to this variant would be predicted to be low,” says Pekosz. Its emergence “could trigger a brand new booster based on its sequence, if this variant truly did become a significant cause of cases.”
For now, the updated fall boosters will likely provide strong protection against currently circulating variants. The CDC and FDA continue monitoring to determine if and when vaccines need tweaking to address BA.2.86.
Some experts say the situation shows the need for adjustable vaccines that can quickly change formulations to match dominant new variants.
Prevention Still Key as New Variants Emerge
BA.2.86 demonstrates the virus continues evolving in ways that may complicate efforts to control transmission.
As population immunity changes, SARS-CoV-2 generates new variants with mutations that enhance infectivity and immune escape. Experts expect more concerning new variants will inevitably emerge.
But JPekosz reiterates BA.2.86 does not warrant panic or new restrictions currently: “There’s no reason for Americans to panic, experts say.”
Continued genomic surveillance, updating vaccines, and layered prevention measures like masking in high-risk settings remain the best ways individuals and public health authorities can respond as the virus adapts.