BA.2.86

BA.2.86 is an Omicron subvariant of SARS-CoV-2, the virus that causes COVID-19. BA.2.86 is notable for having more than thirty mutations on its spike protein relative to BA.2. The subvariant, which was first detected in a sample from 24 July 2023, is of concern due to it having made an evolutionary jump on par with the evolutionary jump that the original Omicron variant had made relative to Wuhan-Hu-1, the reference strain first sequenced in Wuhan in December 2019. It is a mutation of BA.2, itself a very early mutation in the Omicron family. BA.2.86 was designated as a variant under monitoring by the World Health Organization on 17 August 2023. The variant was nicknamed Pirola by T. Ryan Gregory, although no official sources use this name. Its descendant JN.1 (BA.2.86.1.1) became the dominating Lineage in Winter 2023/2024.

Affected countries
BA.2.86 was first reported by Denmark and Israel. On 18 August 2023, when only six cases had been reported from four countries (Denmark, Israel, the United Kingdom and the United States), the British healthcare authorities noted that its almost simultaneous appearance in several countries still operating detailed genomic surveillance indicated that it likely already was spreading more widely internationally, a view also shared by other experts. There has been an overall significant decrease in sequencing (ten times as many samples were uploaded to GISAID in August 2022 compared to July 2023), reducing the possibility of tracking variants globally.

As of 30 August, 24 cases of BA.2.86 had been detected in Canada, Denmark, Israel, Portugal, South Africa, Sweden, the United Kingdom and the United States (three states, including one detected in an airport in a traveller who had just arrived from Japan). As of 2 September, it had also been detected in wastewater in a number of places where not yet confirmed directly in samples from people, including one U.S. state (earliest U.S. detection in a wastewater sample from late July), Switzerland (where it made up c. 2% of coronavirus particles in a wastewater sample from one region in early August), Norway, Germany, Spain, Thailand (detection in a wastewater sample from late July) and Hong Kong.

Immunity, contagiousness and virulence
Initially it was feared that BA.2.86 would be able to partially evade earlier immunity. However by November evidence indicated that it was not resistant to existing antibodies. The CDC and WHO assessed that the "public health risk posed by this variant is low compared with other circulating variants". Moderna and Pfizer have stated that their COVID-19 vaccines targeted at the omicron variant remain effective against BA.2.86 and Novavax has stated its updated protein-based COVID-19 vaccine appears effective against "Pirola" as well.

As of late August, there had been too few known cases over a relatively short period to accurately evaluate its symptoms and severity, but there were indications that it may be similar to other circulating variants: In three early cases from Denmark and one from Canada, the local authorities reported that symptoms had been similar to those typically seen in COVID-19, none of the small number of globally known cases were reported to have died, and in parts of the U.S. where it had been detected there had not been a disproportionate increase in hospitalizations.

Initial lab results from China and Sweden indicate that the variant is neither as contagious nor immune-evasive as some scientists had feared, and is no longer regarded as "the second coming of Omicron". Two studies published in Cell suggest, that while BA.2.86 has reported to have been less contagious, it may lead to more severe disease by entering further into the lower lungs.

Nomenclature
Some news media have used the colloquial name "pirola" to describe the BA.2.86 variant. The name is reported to have been created by a social media user by combining the names of the Greek letters pi and rho, which follow the letter omicron in the Greek alphabet.