BA.2.86

"JN.1" redirects here. For other uses, see JN1 (disambiguation).

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.^[1] The subvariant, which was first detected in a sample from 24 July 2023,^[2] 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.^[3][4][5][6] It is a mutation of BA.2, itself a very early mutation in the Omicron family.^[4] BA.2.86 was designated as a variant under monitoring by the World Health Organization on 17 August 2023.^[7] The variant was nicknamed Pirola by media, although no official sources use this name.^[8] Its descendant JN.1 (BA.2.86.1.1) became the dominating Lineage in Winter 2023/2024.^[9][10]

Affected countries

BA.2.86 was first reported by Denmark and Israel.^[1][11] 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,^[11] a view also shared by other experts.^[12] 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.^[1][3]

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).^[13] 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),^[3][14] Switzerland (where it made up c. 2% of coronavirus particles in a wastewater sample from one region in early August),^[3][15] Norway,^[16] Germany,^[17] Spain, Thailand (detection in a wastewater sample from late July)^[18][13][19] and Hong Kong.^[20]

Biology

Immunity, contagiousness and virulence

The genomic sequence of the Pirola variant (JN.1) is pictured above

Initially it was feared that BA.2.86 would be able to partially evade earlier immunity.^[1][3][21] However by November evidence indicated that it was not resistant to existing antibodies.^[22] The CDC and WHO assessed that the "public health risk posed by this variant is low compared with other circulating variants".^[23] Moderna and Pfizer have stated that their COVID-19 vaccines targeted at the omicron variant remain effective against BA.2.86 ^[24] and Novavax has stated its updated protein-based COVID-19 vaccine appears effective against "Pirola" as well.^[25]

As of late August, there had been too few known cases over a relatively short period to accurately evaluate its symptoms and severity,^[1] 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,^[13] none of the small number of globally known cases were reported to have died,^[26] and in parts of the U.S. where it had been detected there had not been a disproportionate increase in hospitalizations.^[3]

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.^[27][28]

JN.1

JN.1 (sometimes referred to as "Pirola"), a subvariant of BA.2.86, emerged during August 2023 in Luxembourg. By December 2023, it had been detected in 12 countries, including the UK and US.^[29][30] On 19 December, JN.1 was declared by the WHO to be a variant of interest independently of its parent strain BA.2.86, but overall risk for public health was determined as low.^[31] With JN.1 accounting for some 60% of cases in Singapore, in December 2023, Singapore and Indonesia recommended wearing masks at airports.^[32] The CDC estimated that the variant accounted for 44% of cases in the US on 22 December 2023 and 62% of cases on 5 January 2024.^[33]

As of 9 February 2024^[update], JN.1 was estimated by the WHO to be the most prevalent variant of SARS-CoV-2 (70–90% prevalence in four out of six global regions; insufficient data in the East Mediterranean and African regions). The general level of population immunity and immunity from XBB.1.5 booster versions of the COVID-19 vaccine was expected to provide some protection (cross-reactivity) to JN.1.^[34]

NB.1.8.1

NB.1.8.1 is a sub-variant of the Omicron lineage of SARS-CoV-2, first identified in early 2025.^[35] It has been detected in more than 20 countries, including the United Kingdom, United States, China, India, Singapore, and Thailand.^[36] The variant has shown signs of increased transmissibility, contributing to a rise in COVID-19 cases in several regions.^[37][38]

Genomic analysis of NB.1.8.1 reveals mutations in the spike protein that may contribute to its spread.^[35] In laboratory studies, NB.1.8.1 has demonstrated a growth advantage over LP.8.1, the SARS-CoV-2 circulating strain that generally predominated worldwide in the first half of 2025.  Research groups in China and Japan have reported that this variant’s growth advantage over LP.8.1 is due to its enhanced infectivity of human cells, not enhanced  immune evasion ability compared  with the currently predominating variant.^[39][40] Globally, NB.1.8.1, accounted for 24% of all sequences submitted to the World Health Organization in the week ending on 01 June 2025 which was an increase from 18% in the week ending on 4 May 2025. LP.8.1 accounted for 21% of all submitted sequences in the week ending on 01 June 2025, a decrease from 33% in the week ending on 4 May 2025.^[41] NB.1.8.1 became detectable in US wastewater at the end of the first week in June 2025.^[42]

Despite its rapid transmission, available data suggest that the variant does not lead to more severe disease compared to earlier strains.^[43][44] Commonly reported symptoms include sore throat, fever, fatigue, cough, muscle aches, and nasal congestion.^[45] The World Health Organization categorized NB.1.8.1 as a VUM in June 2025.^[45]

XFG

Late in January 2025, XFG (sometimes referred to as "Stratus")^[46] was discovered in Canada.^[47] XFG is a recombination of two subvariants: LF.7 and LP.8.1.2. In late May 2025, WHO reported that XFG was the 2nd most common variant globally, making up 22.7% of all global cases, behind NB.1.8.1 (named "Nimbus", often with extremely sore throat)^[48] with 24.9% of global cases, and closely followed by LP.8.1 accounting for 22.6% of global cases.^[49] In late June 2025, CDC estimate data showed XFG was the 3rd-most common U.S. variant, with 14% of all cases, behind NB.1.8.1 and LP.8.1, which account for 43% and 31% of all cases respectively.^{[citation needed]}

Other sublineages

Late in April 2024, CDC data showed KP.2 to be the most common U.S. variant, with a quarter of all cases, just ahead of JN.1. KP1.1 represented 7 percent of U.S. cases.^[50] These two are sometimes referred to as the 'FLiRT' variants because they are characterized by a phenylalanine (F) to leucine (L) mutation and an arginine (R) to threonine (T) mutation in the virus's spike protein.^[51] By July 2024, a descendant of KP.2 with an extra amino acid change in the spike protein, Q493E, was given the names KP.3 and, informally, 'FLuQE,' and became a major variant in New South Wales during the Australian winter. Initial research suggested that the Q493E change could help KP.3 be more effective at binding to human cells than KP.2.^[52]

Early in August 2024, XEC was discovered in Germany.^[53] XEC is a recombination of two subvariants: KS.1.1 and KP.3.3. In early December 2024, CDC data showed XEC to be the most common U.S. variant, with 45% of all cases, ahead of KP3.1.1, which accounted for 24% of all cases.^[54]

On 14 September 2025, WHO listed JN.1 as a VOI; and KP.3.1.1, LP.8.1, NB.1.8.1, XEC, and XFG as VUMs. The estimated prevalence for the week ending 7 September 2025 was 68% for XFG (an increase compared to 61% for the week ending 10 August), 20% for NB.1.8.1 (a decrease compared to 24% for the week ending 10 August), and 4% or lower for the other four variants.^[55] In late September, the ECDC listed no VOCs, and listed BA.2.86 as a VOI, and NB.1.8.1 and XFG as VUMs.^[56]

Nomenclature

Some news media have used the colloquial name "pirola" to describe the BA.2.86 variant.^[57][58] 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.^[59]

See also

• COVID-19 portal
• Viruses portal

• Antigenic shift
• Saltation (biology)
• Timeline of the SARS-CoV-2 Omicron variant
• Variants of SARS-CoV-2
  • Other variants of either interest or concern: Alpha, Beta, Gamma, Delta, Epsilon, Zeta, Eta, Theta, Iota, Kappa, Lambda, Mu
• Sikhulile Moyo, the scientist who discovered SARS-CoV-2 Omicron