https://www.who.int/publications/m/item/covid-19-epidemiological-update---22-december-2023
SARS-CoV-2 variants of interest and variants under monitoring
Geographic spread and prevalence
Globally, during the 28-day period from 20 November to 17 December 2023, 22 413 SARS-CoV-2 sequences were shared through GISAID. In comparison, in the two previous 28-day periods, there were 62 927 and 77 550 sequences shared, respectively. As there is usually a several-week average delay between case incidence and sequence reporting, it remains to be seen whether there will be an increase in reported sequences in the coming weeks commensurate to the current increase in new cases reported, or whether this decline in reported sequences will persist as countries continue to scale down sequencing. The data are periodically updated to retrospectively include sequences with earlier collection dates, so the number of submissions in a given time period may change.
WHO is currently tracking several SARS-CoV-2 variants, including:
• Five variants of interest (VOIs): XBB.1.5, XBB.1.16, EG.5, BA.2.86 and JN.1
• Five variants under monitoring (VUMs): DV.7, XBB, XBB.1.9.1, XBB.1.9.2 and XBB.2.3
Table 6 shows the number of countries reporting VOIs and VUMs, and their prevalence from epidemiological week 44 (30 October to 5 November 2023) to week 48 (27 November to 3 December 2023).
Globally, EG.5 remains to be the most reported VOI (now reported by 93 countries), however it has shown declining trends over the past few weeks, accounting for 36.3% of sequences in week 48 compared to 53.7% in week 44.
JN.1, a sub-lineage of the BA.2.86 Omicron variant, was designated a VOI on 18 December 2023, due to its rapid increase in prevalence in recent weeks. Previously WHO was tracking it as part of the BA.2.86 VOI. JN.1 accounted for 27.1% of SARS-CoV-2 sequences in week 48 compared to 3.3% in week 44. This is a notable increase when comparing to its parent lineage, BA.2.86, which accounted for 5.9% of sequences in week 48 compared to 4.4% in week 44. The initial risk evaluation for JN.1 was published on 18 December 2023, with an overall evaluation of low additional public health risk at the global level based on available evidence.
The other VOIs, XBB.1.5 and XBB.1.16, have decreased in global prevalence, respectively, during the same period:
XBB.1.5 accounted for 7.3% of sequences in week 48, a slight decrease from 8.2% in week 44; XBB.1.16 accounted for 4 .2% of sequences in week 48, a decrease from 9.6% in week 44 (Figure 10, Table 6).
All VUMs have shown a decreasing trend over the reporting period (Table 6).
Sufficient sequencing data to calculate variant prevalence at the regional level during weeks 44 to 48 were available from three WHO regions: the Region of the Americas, the Western Pacific Region, and the European Region (Table 7).
Among the VOIs, JN.1 was the most reported variant and showed an increasing trend in the European and Western Pacific regions, whilst EG.5 remained the most reported variant in the Regions of the Americas.
BA.2.86, XBB.1.5 and XBB.1.16 showed increasing or stable trends in all three regions.
All VUMs in all three regions observed decreasing or stable trends.
With declining rates of testing and sequencing globally (Figure 10), it is increasingly challenging to estimate the severity impact of emerging SARS-CoV-2 variants. There are currently no reported laboratory or epidemiological findings indicating any association between VOIs/VUMs and increased disease severity.
As shown in Figure 9 and Figure 10, low and unrepresentative levels of SARS-CoV-2 genomic surveillance continue to pose challenges in adequately assessing the variant landscape.
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