Attention of late has been focused on Omicron subvariant "Eris". But the latest COVID variant BA.2.86 is being described as "radically different".
Health authorities are tracking yet another new variant of COVID-19 which has a large number of mutations.
The new lineage, named BA.2.86 was classified as a "variant under monitoring" last week by the World Health Organization (WHO).
There is no evidence that it spreads faster or causes more severe illness, but scientists are keeping an eye on the variant that has been found in Denmark, the UK, the US and Israel.
What are the latest variants that authorities are tracking?
COVID infections and hospitalisations have already been rising in the US, Europe and Asia, with many cases this summer attributed to the EG.5 "Eris" subvariant, a descendant of the Omicron lineage.
Public health authorities are now tracking another variant, BA.2.86, due to its more than 30 mutations.
BA.2.86 stems from an "earlier branch" of the coronavirus, so it differs from the variant targeted by current vaccines, said Dr S. Wesley Long, medical director of diagnostic microbiology at Houston Methodist Hospital.
He said it remains to be seen whether BA.2.86 will be able to out-compete other strains of the virus or have any advantage in escaping immune responses from prior infection or vaccination.
One of the reasons that EG.5 was moved up by WHO to become a "variant of interest" was that it has increased in prevalence compared to other variants, for instance.
'Radically different in structure'
With many countries having drastically reduced testing of COVID-19 cases, it can complicate efforts to find new variants.
In that situation, the trajectory of BA.2.86 "doesn't look good right now," given the speed at which new cases are being identified, said Dr Eric Topol, a genomics expert and director of the Scripps Research Translational Institute in La Jolla, California.
Its many mutations make BA.2.86 "radically different in its structure" compared to earlier variants, Topol said.
The main question, he added, is whether BA.2.86 will turn out to be highly transmissible.
WHO has urged countries to continue surveillance and sequencing of COVID-19 cases but said that there was very "limited information available right now" on BA.2.86.
Will people have a more severe illness with these variants?
Wider spread of BA.2.86 would likely cause more illness and death in vulnerable populations, Topol said.
But it is too soon to know whether BA.2.86 will cause more severe illness.
"Based on the available evidence, we do not yet know what risks, if any, (BA.2.86) may pose to the public's health beyond what has been seen with other currently circulating lineages," a US Centres for Disease Control and Prevention (CDC) spokesperson said.
Rowland Kao at the University of Edinburgh told Euronews Next last week that if a new variant were to drive an increase in COVID-19 cases, the number of hospitalisations in combination with other viruses could cause problems for healthcare systems.
Are vaccines going to be effective against new variants?
"The vaccine is still going to provide you great defence against illness and death," Long said.
The COVID booster doses that are now being developed were made to target the XBB subvariant of Omicron.
Moderna recently announced that its updated COVID booster vaccine demonstrated an immune response against the EG.5 and FL.1.5.1 variants. The vaccine also showed it was effective against the circulating XBB strains of Omicron.
Pfizer also has said its updated COVID-19 shot showed neutralising activity against the Eris subvariant in a study conducted on mice.