The World Health Organization has recently heightened its scrutiny of the BA.2.86 coronavirus strain and its various derivatives, upgrading its classification to a “variant of interest.” Despite this, the organization suggests that the current risk posed by this group of viruses remains relatively low.
Previously, this lineage had been monitored by the organization under the classification of a “variant under monitoring.”
Alongside BA.2.86, WHO has now identified XBB.1.5, XBB.1.6, and EG.5 as other variants of interest. At present, there are no variants classified as of concern, the highest level of designation.
First detected in the United States in August, BA.2.86 has now become the third most prevalent variant, contributing to an estimated 1 in 11 new cases of Covid-19 in the country, according to the most recent update from the US Centers for Disease Control and Prevention’s variant tracker. Although its prevalence seems to have tripled in the last two weeks, it’s commonly observed that a variant’s growth is initially overestimated in the early stages of its appearance in the CDC’s monitoring.
But if BA.2.86 doesn’t seem to pose a significant threat, why has WHO elevated its status?
“We’ve noticed a gradual and consistent rise in its identification across the globe,” explained Dr. Maria Van Kerkhove, WHO’s technical lead on Covid-19, in a video shared on social media. “Characterizing it as a variant of interest truly aids in enhancing surveillance for these kinds of variants globally and also stimulates research to comprehend whether they lead to more severe illnesses or have increased immune evasion capabilities,” she remarked.
A slow build
BA.2.86, often referred to by some virus observers as Pirola, sparked intense research interest when it came to public attention during the summer. This variant shares numerous characteristics with BA.1, the original Omicron strain of the coronavirus, which led to widespread transmission, resulting in a surge in hospitalizations and deaths worldwide.
With over 30 mutations in its spike proteins, BA.2.86 differed genetically from earlier versions of the virus causing Covid-19. Initially, scientists were concerned that it might entirely bypass the immunity provided by vaccinations and previous infections, potentially fueling another wave of infections.
However, puzzlingly, BA.2.86 didn’t exhibit the same rapid spread as the initial Omicron strain. Some studies suggested that as it accumulated new mutations, this variant lost some of its ability to infect human cells, slowing down its propagation.
Other research indicated that it didn’t entirely evade the body’s immune response, and the current Covid-19 vaccine, designed to combat the XBB.1.5 subvariant, offered a level of protection against it, which was seen as positive news.
However, experts who track variants cautioned that while the original BA.2.86 virus may have been less threatening, it was continually evolving, and one of its descendants might regain enough potency to become a significant concern.
Indeed, BA.2.86 continues to evolve and produce more robust offspring, as noted by Dr. Jesse Bloom, a computational virologist at the Fred Hutchinson Cancer Center in Seattle.
Bloom highlighted studies conducted by researchers at Columbia University and in China, demonstrating that the JN.1 subvariant possesses a genetic alteration enhancing its ability to evade our immune defenses, albeit moderately: a roughly twofold decrease in our antibodies’ ability to neutralize the virus.
However, even this slight modification seems to have provided it with an advantage over its predecessor.
“In terms of adaptability, what we’re observing is that JN.1 is increasing in numbers at a faster rate than its parent, BA.2.86,” Bloom stated.
Meanwhile, the distantly related XBB lineage of viruses, now comprising several swifter and more adaptable descendants like HV.1, is gaining prevalence. HV.1 currently stands as the dominant lineage in the US, accounting for about 1 in 3 new cases of Covid-19, according to the CDC.
“From a scientific perspective, all these variants are currently in motion, and either family might spread. It’s hard to precisely predict what this will mean for Covid case counts and the disease burden in the upcoming winter,” Bloom commented.
Dearth of data makes predictions difficult
Several countries have witnessed an increase in case numbers as BA.2.86 and JN.1 have spread, noted Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.
“In Europe, it has been linked in several countries to a significant rise in case numbers, but in other countries, it hasn’t. So, what’s the reason?” he questioned.
One major challenge is the scarcity of data, according to Dr. Peter Hotez, a pediatric infectious disease specialist at the Baylor College of Medicine and Texas Children’s Hospital, who contributed to the development of a Covid-19 vaccine.
“Interpreting the situation is more difficult now because surveillance efforts are reduced. Therefore, predictions have to rely on a combination of factors like wastewater analysis, hospital admissions, and the percentage of positive cases,” Hotez explained.
Despite the limited available data, Hotez suggests exercising caution in the upcoming weeks based on the visible indicators.
Covid-19 hospitalizations, which had been declining, have begun to show a slight increase. Last week, over 18,000 Americans were hospitalized with Covid-19, marking a 10% rise compared to the previous week, as per CDC data. Nationally, levels of coronavirus in wastewater remain high and seem to be on the rise, possibly indicating a forthcoming increase in case numbers.
Simultaneously, only a mere 16% of American adults and a mere 6% of children have received the latest Covid-19 vaccine, which studies have demonstrated to significantly enhance antibodies against the XBB family of viruses and offer some defense against the BA.2.86 family, albeit to a lesser extent.
A recent study conducted by microbiologist and immunologist Dr. David Ho and his team at Columbia University revealed that while last year’s booster – designed to counteract two versions of the virus causing Covid-19, the original strain, and BA.5 – didn’t seem to sufficiently readjust our immunity against the latest variants as anticipated, this year’s single-strain shot has shown remarkable efficacy.
The approach of reverting to a single-strain shot and boosting immunity against the dominant leading variant appears to have yielded positive results, amplifying antibodies roughly 27-fold against the current spectrum of variants, including JN.1.
Bloom views this as encouraging news, as it indicates that the strategy of refining the Covid-19 vaccine annually should continue to mitigate the most severe outcomes of infections, provided individuals get vaccinated.
However, the low uptake of vaccines implies a larger pool of susceptible adults and children who might be prone to breakthrough infections or reinfections with Covid-19.
“I believe we might observe an uptick in numbers as we head into the holiday season,” remarked Hotez. “We need to intensify our efforts to encourage more Americans to take the booster shot. That’s currently the most crucial action item.”
