Table 2.

Omicron subvariants under monitoring (as of 9 February 2023).

Pango Lineage #. (+Mutation)	GISAID Clade	Next Strain Clade	Relationship to Circulating VOC Lineages	Spike Genetic Features	Earliest Documented Samples	Pathophysiology	Epidemiology
BF.7 *	GRA	22B	BA.5 sublineages	BA.5 + S:R346T	24 January 2022	-first detected 13 May 2022 in Belgium -spike protein mutations (at amino acid R346T) leading to their ability to escape neutralizing antibody [46] -R346T may contribute to reduced sensitivity to mAbs, increased binding to (ACE2) receptor, and increased expression of the RBD [47,48,49]	-As of 4 October 2022, 9809 sequences of the BF.7 sublineage have been reported globally and are mostly prevalent in Europe [46]
BQ.1 $	GRA	22E	BA.5 sublineages	BQ.1 and BQ.1.1: BA.5 + S:R346T, S:K444T, S:N460K	7 February 2022	-currently, there are no epidemiologic data that show an increase in disease severity	-has a prevalence of 6% and has been detected in 65 countries [50] -no data on severity or immune escape from studies in humans
BA.2.75 §	GRA	22D	BA.2 sublineage	BA.2.75: BA.2 + S:K147E, S:W152R, S:F157L, S:I210V, S:G257S, S:D339H, S:G446S, S:N460K, S:Q493R reversion	31 December 2021	-additional mutations may be capable of escaping neutralizing antibodies [51]	-first detected in India in May 2022 [52]
CH.1.1 §	GRA	22D	BA.2 sublineage	BA.2.75 + S:L452R, S:F486S	27 July 2022	-mutation in the L452R substitution in the spike protein (previously discovered in the Delta and Omicron BA.4/5 variants) [53] -lower infectivity, highly resistance to neutralization by bivalent sera, lower efficiency of syncytia formation [54]	-as per reported by CDC, CH1.1 is the 5th most spreading variants, which accounted for 1.6% of total new cases in the U.S. [54] -as of January 15, it was detected in the U.K., where it accounted for 28.2% of new sequence infections compared to XBB.1.5′s 10.9% [54]
XBB µ	GRAA	22F	Recombinant of BA.2.10.1 and BA.2.75 sublineages, i.e., BJ1 and BM.1.1.1, with a breakpoint in S1	BA.2+ S:V83A, S:Y144-, S:H146Q, S:Q183E, S:V213E, S:G252V, S:G339H, S:R346T, S:L368I, S:V445P, S:G446S, S:N460K, S:F486S, S:F490S	13 August 2022	-early evidence pointing at a higher reinfection risk as compared to other circulating Omicron sublineages -currently, no available data to support escape from recent immune responses induced by other Omicron lineages [55] -further studies are needed, the current data do not suggest there are substantial differences in disease severity for XBB * infections	-has a global prevalence of 1.3% and it has been detected in 35 countries [55]
XBB.1.5	GRA	23A	Recombinant of BA.2.10.1 and BA.2.75 sublineages, i.e., BJ1 and BM.1.1.1, with a breakpoint in S1	XBB + S:F486P	15 January 2022	-further studies are needed; the current data do not suggest there are substantial differences in disease severity for XBB * infections	-as of January 15, it was detected in the U.K., where it accounted for 10.9% of new sequence infections [54]
XBF	GRA		Recombinant of BA.5.2.3 and CJ.1 (BA.2.75.3 sublineage)	BA.5 + S:K147E, S:W152R, S:F157L, S:I210V, S:G257S, S:G339H, S:R346T, S:G446S, S:N460K, S:F486P, S:F490S	27 July 2022	-further studies are needed; the current data do not suggest there are substantial differences in disease severity for XBB * infections	-responsible for the recent surge of COVID cases in Australia [55] -first case detected in the Philippines on 28 January 2023 (specimens collected in December 2022) [56] * very little to no information on XBF, mainly reported on online newspaper only.

# includes descendent lineages; * additional mutations outside of the spike protein: N: G30, S33F, ORF9b: M26, A29I, V30L; ^$ additional mutation outside the spike protein: ORF1a: Q556K, L3829F, ORF1b: Y264H, M1156I, N1191S, N: E136D, ORF9b: P10F; ^§ additional mutations outside of the spike protein: ORF1a: S1221L, P1640S, N4060S, ORF1b: G662S, E: T11A; ^µ additional mutations outside of the spike protein: ORF1a: K47R, ORF1b: G662S, S959P, E: T11A, ORF8: G8*.