Living Evidence - SARS-CoV-2 variants
Living evidence tables provide high level summaries of key studies and evidence on a particular topic, and links to sources. They are reviewed regularly and updated as new evidence and information is published.
Viruses constantly change through mutation and over time, new variants of a virus are expected to occur. Some variants have characteristics that have a significant impact on transmissibility, severity of disease and effectiveness of vaccines.
Currently, the World Health Organization has identified one currently circulating variant of concern: Omicron. This table includes information on Omicron subvariants that are currently causing concern in the scientific community and under monitoring by the World Health Organization.
Regular checks are conducted for new content and any updates that occur during the week are highlighted. All highlights are removed each Monday.
| Topic | BF.7 | BQ.1 | BA.2.75 | CH.1.1 | XBB | XBB.1.5 | XBF |
|---|---|---|---|---|---|---|---|
| Mutations | BA.5 + S:R346T It is a BA.5 sublineage. | One or several of the five mutations: S:R346X, S:K444X, S:V445X, S:N450D, and S:N460X It is a BA.5 sublineage. BQ.1 and BQ.1.1 have additional spike mutations S:K444T, S:N460K, and S:R346T | S:D339H, S:G446S, S:N460K, and S:Q493R reversion It is a BA.2 sublineage. BA.2.75.2 has additional spike mutations S:R346T, S:F486S, and S:D1199N. | BA.2.75 + S:L452R, S:F486S It is a BA.2.75 sublineage. | S:G339H, S:R346T, S:L368I, S:V445P, S:G446S, S:N460K, S:F486S, and S:F490S It is a recombinant of BA.2.10.1 and BA. 2.75. XBB.1.5 has an additional spike mutation S:F486P. | XBB + S:F486P | BA.5 + S:K147E, S:W152R, S:F157L, S:I210V, S:G257S, S:G339H, S:R346T, S:G446S, S:N460K, S:F486P, S:F490S It is a recombinant of BA.5.2.3 and CJ.1 |
| Transmissibility | Has a growth advantage over BA.5. ACE2-binding affinity: similar to BA.4/5. | Has a growth advantage over BA.5.2. ACE2-binding affinity: | Has a growth advantage over BA.5.2. | Has a growth advantage over BQ.1.1. | Has a growth advantage over BA.5.2. Has a growth advantage over BA.5.2. ACE2-binding affinity: XBB/XBB.1: weaker than BA.2*^ | Has a growth advantage over other circulating Omicron sublineages, including BQ.1.1. ACE2-binding affinity: substantially higher than BQ.1.1 and XBB/XBB.1 XBB.1.5 has more than 1.2-fold greater relative effective reproduction number than XBB.1. | Insufficient data |
| Virulence and severity | Insufficient data | Preliminary analysis of the risk of hospital admission following presentation to emergency care shows no increase in risk for BQ.1 compared to BA.5. | Insufficient data | Preliminary analysis of the risk of hospital admission following presentation to emergency care shows no increase in risk for CH.1.1 compared to BA.5. | Insufficient data | Preliminary analysis suggests that no change in disease severity. | Insufficient data |
| Impact on immunity | More resistant to the neutralisation antibodies induced by prior vaccination and infection than BA.4/5. Less resistant to the neutralisation antibodies induced by prior vaccination and infection than BQ.1 and BQ.1.1. | In-vitro studies show that BQ.1 and BQ.1.1 are more resistant to the neutralisation antibodies induced by prior infection and vaccination (including booster) than BA.5. BA.5-adapted bivalent booster vaccine elicited better neutralising response against BQ.1.1 than the original monovalent booster vaccine. Previous infection enhanced the magnitude and breadth of BA.5-bivalent-booster-elicited neutralisation. | More neutralisation resistant to sera from vaccinated/boosted individuals than BA.2. Less neutralisation resistant to sera from vaccinated/boosted individuals than BA.4/5. Less neutralisation resistant to sera from unvaccinated individuals who had recovered from BA.1 or BA.2 infections than BA.5. BA.1-adapted and BA.4/5-adapted bivalent booster vaccines elicited better neutralising titres against BA.2.75 than the original monovalent booster vaccine. elicited higher neutralising titres against BA.2.75 than against BA.4 and BA.5. A real-life study suggested that previous infection with BA.5 or BA.4 provided better protection against BA.2.75 than previous infection with BA.1 or BA.2 (~80% versus 50%). | More resistant to the neutralisation antibodies induced by prior infection and vaccination than BA.2, BA.4/5 and XBB. | XBB.1 and XBB.3 variants were more resistant to the neutralisation antibodies induced by prior vaccination (either primary or booster) and prior infection than BA.2, BA.4/5, BQ.1.1 and BA.2.75.2. BA.4/5-adapted bivalent booster vaccines elicited better neutralising response against XBB.1 than original monovalent booster vaccine. The neutralising response elicited by the bivalent vaccine against XBB.1 was further enhanced in individuals with a prior infection history. A real-life study suggested that the bivalent mRNA booster vaccine effectiveness against symptomatic XBB/XBB.1.5 infection in persons who had previously received 2–4 monovalent vaccine doses ranged from 38% to 48% at 2-3 months after vaccination. | XBB.1.5 is equally immune evasive as XBB.1 but slightly less resistant to neutralising antibodies induced by BA.1, BA.5, and BF.7 breakthrough infections.^ XBB.1.5 is highly resistant to monovalent vaccine elicited antibody neutralisation. Bivalent vaccine restores the antibody response. | Insufficient data |
| Treatment | Not sensitive to neutralisation by tixagevimab + cligavimab. | BQ.1.1 not sensitive to neutralisation by imdevimab + casirivimab and tixagevimab + cligavimab. Mixed findings for BQ.1.1 sensitivity to sotrovimab. One study reported no sensitivity; while the other reported reduced sensitivity compared to BA.5 and increased sensitivity compared to BA.2.^ BQ.1.1 had similar susceptibility to remdesivir, molnupiravir and nirmatrelvir compared to the ancestral strain. | More sensitive to neutralisation by sotrovimab than BA.2, but less sensitive than BA.5. Less sensitive to neutralisation by cilgavimab than BA.2 and BA.5 More sensitive to neutralisation by tixagevimab than BA.2 and BA.5 Not sensitive to neutralisation by imdevimab More sensitive to neutralisation by casirivimab than BA.2 and BA.6 Remdesivir, molnupiravir, and nirmatrelvir retained neutralising activities against BA.2.75. | Insufficient data | Not sensitive to neutralisation by imdevimab + casirivimab and tixagevimab + cligavimab. Mixed findings for sotrovimab; In one study, XBB.1 was sensitive to neutralisation by sotrovimab,^ while in the other it was not sensitive. Similar susceptibility to remdesivir, molnupiravir and nirmatrelvir compared to the ancestral strain. | Not sensitive to neutralisation by Evusheld (tixagevimab + cligavimab), but weakly sensitive to sotrovimab. Susceptible to neutralisation by remdesivir, molnupiravir, nirmatrelvir. | Insufficient data |
| Countries reporting detection | 100 | 123 | 112 | 67 | 39 |
The World Health Organization (WHO) announced the Variant naming system on 1 June 2021.
Details are tabulated when Variants meet the World Health Organization (WHO) definition of Variant of Concern (VOC).
- Previously circulating VOC listed by WHO: Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1) and Delta (B.1.617.2)
- Variant of Concern lineages under monitoring (VOC-LUM) by WHO: BF.7, BQ.1, BA.2.75, CH.1.1, XBB, XBB.1.5 and XBF.
- Previously circulating Variants of Interest by WHO: Epsilon, Zeta, Eta, Theta, Iota, Kappa, Lambda, Mu
- Recombinant lineages: XD and XF (combination of Delta AY.4 and BA.1, XD has the Omicron S gene incorporated into a Delta genome), XE (combination of BA.1 and BA.2, with the majority of the genome including the S gene belonging to BA.2), and XBB (combination of BA.2.10.1 and BA.2.75 sublineages, i.e. BJ1 and BM.1.1.1, with a breakpoint in S1). The XD recombinant is now classified as a formally monitored variant (FMV) by WHO and XE is being tracked as part of the Omicron variant.
Notes
*Preliminary data, not fully established, in some cases small numbers or short follow up; interpret with caution
^ Commentary grey literature, pre-peer review or news
The "last updated" date refers to the date when the evidence was last reviewed.
Background
Evidence check - Emerging variants (PDF)
Evidence check - Omicron (BA.2 sub-lineage) (PDF)
Living evidence tables include some links to low quality sources and an assessment of the original source has not been undertaken. Sources are monitored regularly but due to rapidly emerging information, tables may not always reflect the most current evidence. The tables are not peer reviewed, and inclusion does not imply official recommendation nor endorsement of NSW Health.
Last updated on 10 Mar 2023