New COVID variant BA.2.86 — nicknamed ‘Pirola’ — is here

Scientists are racing to understand a new COVID-19 strain dubbed BA.2.86 and assess its potential for fueling a fresh autumn surge of cases. 

The lineage, informally called “Pirola” on social media, has garnered attention due to its substantial genetic deviations from other omicron subvariants that have been the prevailing strains of COVID-19 for the past two years.

In a risk assessment issued last week, the U.S. Centers for Disease Control and Prevention noted that the new variant may be better able to cause breakthrough infections than previous strains of the virus. 

“BA.2.86 may be more capable of causing infection in people who have previously had COVID-19 or who have received COVID-19 vaccines,” the report said.

It’s a concerning prospect as all key disease indicators in the United States show an upward trajectory. In the month ending on Aug. 18, COVID-related hospitalizations rose by 87%, translating to over 2,152 daily admissions, according to the CDC’s latest data. Simultaneously, COVID-19 fatalities increased by 70% compared with the previous month.

While the late-summer COVID bump is likely driven by offshoots of the omicron XBB subvariant, with EG.5 making up more than 20% of new cases last week, BA.2.86 could quickly change the picture.

What makes BA.2.86 different from other variants?

What distinguishes BA.2.86 from other variants is its substantial mutation count within its spike protein, which is what facilitates the virus’ entry into human cells. 

“If you go from XBB.1.5 to EG.5, it’s only 1-2 differences in mutations,” said Dr. Peter Chin-Hong, an infectious diseases expert with UCSF. “But when you go from XBB.1.5 to BA.2.86, it’s a jump of about 36 mutations. The last time we saw that was from delta to omicron.”

BA.2.86, designated as a “variant under monitoring” by the World Health Organization, first surfaced in Denmark in late July and subsequently appeared in the United States in August. Given the absence of a discernible link between the earliest reported cases, it is likely that the variant is already circulating widely.

“When omicron hit in the winter of 2021, there was a huge rise in COVID-19 cases because it was so different from the delta variant, and it evaded immunity from both natural infection and vaccination,” Dr. Scott Roberts, an infectious diseases expert with Yale Medicine, said in a weekly briefing. “The other concern is that this strain has been picked up in at least six countries, and the cases are unrelated. This suggests some degree of transmission in the community that we’re not detecting.”

The CDC has not yet included BA.2.86 in its biweekly variant proportions chart, as its prevalence in the U.S. remains relatively low. Whether BA.2.86 will dominate or diminish in the presence of other strains remains uncertain.

“We are seeing only a handful of cases right now, and we are watching that closely,” Dr. Mandy Cohen, the director of the CDC, said in a call with reporters last week. “The good news is we have the ability to detect and understand this virus and learn more.”

What are the symptoms of BA.2.86?

Scientists do now yet know whether BA.2.86 will cause more severe illness. 

“Based on the available evidence, we do not yet know what risks, if any, it may pose to the public’s health beyond what has been seen with other currently circulating lineages,” the CDC said. 

Confirmed cases of BA.2.86 infection have predominantly exhibited mild symptoms akin to those triggered by earlier variants, including runny nose, headache, fatigue, sneezing and a sore throat. 

“What we would need to make sure we understand is the full spectrum of disease that is caused by BA.2.86. My reservation in giving a lot of detail around this is I don’t want to draw any conclusions coming from eight or nine patients,” Dr. Maria Van Kerkhove, the WHO’s COVID-19 technical lead, told reporters last week.

The number of mutations raises the possibility of increased transmissibility or lethality, especially among high-risk individuals, said Chin-Hong.

Why do some people call it ‘Pirola’?

While some media reports and social media posts have unofficially referred to BA.2.86 as “Pirola,” the WHO has revised its naming system, reserving Greek alphabet labels and nicknames solely for variants of concern like delta and omicron, not for variants under monitoring or of interest.

“We will use a Greek letter when we have a variant of concern, and we won’t hesitate to use those Greek letters should they be needed,” Van Kerkhove said.

What remains uncertain is if BA.2.86 will gain traction. There have been hundreds of mutations to the SARS-CoV-2 virus since it first appeared more than three years ago, and many different strains have disappeared.

Early results from two recent laboratory studies researching the antibody neutralization of BA.2.86 suggest that it may not be any more immune-evasive than currently circulating variants.

“Previously, before much of the population had some form of immunity, a new variant meant a new wave of infections. It’s a very different situation now,” Dr. Anne Hahn, who leads the SARS-CoV-2 Genomic Surveillance Initiative at Yale, said in a bulletin. “We see a lot of variants that could possibly be concerning, but never really take off. So it’s a bit hard to say at this point how dangerous these new variants are.”

Source link

Rate this post

Leave a Comment