Explainer | Do I need to worry about Covid again, after the discovery of Eris, BA.2.86?

The World Health Organization and the US Centres for Disease Control and Prevention are tracking a new, highly mutated lineage of the virus that causes Covid-19.

Six cases in four countries have been detected since late July. Scientists are keeping an eye on the new lineage, named BA.2.86, because it has 36 mutations that distinguish it from the currently-dominant XBB.1.5 variant.

So far there is no evidence that BA.2.86 spreads faster or causes more serious illness than previous versions. The CDC said its advice on protecting yourself from Covid remains the same.

What is new about Covid?

Covid infections and hospitalisation have been rising in the US, Europe and Asia, with more cases in recent months attributed to the EG.5 “Eris” subvariant, a descendant of the Omicron lineage that originally emerged in November 2021.

Over the past few days, public health authorities have documented one case each of BA.2.86 in the United States, the UK, and Israel, and three cases in Denmark.

What do scientists say about BA.2.86?

BA.2.86 stems from an “earlier branch” of the coronavirus, so it differs from the variant targeted by current vaccines, explained 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.