https://www.who.int/news/item/23-12-2024-statement-on-the-antigen-composition-of-covid-19-vaccines
- Currently circulating SARS-CoV-2 variants are all derived from JN.1.
The weekly proportion of XEC sequences among all SARS-CoV-2 sequences
submitted to GISAID continues to increase, while the weekly proportions
of all other Variants of Interest (JN.1) or Variants Under Monitoring
(KP.2, KP.3, KP.3.1.1, JN.1.18 and LB.1) are now declining. There are
other JN.1-derived variants that are currently in low proportions, but
which have mutations that may give them an advantage over XEC: currently
LP.8.1, NP.1, LF.7.2 are variants being monitored and/or characterized.
- In
published and unpublished data using antisera from naïve animal models,
circulating JN.1-derived variants (JN.1, JN.1.16.1, KP.2, KP.2.3, KP.3,
KP.3.1.1, LB.1 and XEC) are antigenically closely related.
...
The timing, specific mutations and antigenic characteristics of emerging
and future variants are difficult to predict, and the potential public
health impact of these variants remain unknown. There are JN.1-derived
variants such as LP.8.1, NP.1 and LF.7.2 that are currently in low
proportions, but which have mutations that may give them more immune
escape than XEC. These will continue to be monitored and/or
characterized. The TAG-CO-VAC strongly supports the ongoing work of the
TAG-VE.
Estimates of VE against recently circulating SARS-CoV-2 variants,
including XBB or JN.1 descendent lineages, are limited in terms of
the number and geographic diversity of studies, vaccine platforms
evaluated, populations assessed, and duration of follow-up.
Furthermore, the referent population for VE estimates varies
substantially with respect to prior history of vaccination. There
are currently no direct comparative estimates for monovalent JN.1,
KP.2 or XBB.1.5 vaccines versus other antigen composition(s)
delivered during the same time period. Finally, VE estimates may be
confounded by differences in undocumented infection-derived
immunity between groups, leading to potential underestimation of
VE (virus evolution)
...
Recommendations for COVID-19 vaccine antigen composition
Given
the breadth in immune responses demonstrated by monovalent JN.1 lineage
vaccines against circulating variants, the TAG-CO-VAC advises retaining
the current COVID-19 vaccine antigen composition, i.e. a monovalent JN.1 lineage variant
(NextStrain: 24A, GenBank: PP298019, GISAID: EPI_ISL_18872762) as one
approach to induce enhanced neutralizing antibody responses to JN.1 and
its descendent variants (e.g., KP.3.1.1 and XEC).
Other
approaches that demonstrate broad and robust neutralizing antibody
responses against currently circulating JN.1 descendent lineage
variants, such as vaccine antigens derived from more recent variants or
alternative formulations, could also be considered.
As per the WHO Director General’s standing recommendations for COVID-19, Member States are recommended to continue to offer COVID-19 vaccination based on the recommendations of the WHO SAGE.
Vaccination should not be delayed in anticipation of access to vaccines
with an updated composition; vaccination programmes can continue to use
any available WHO emergency-use listed or prequalified COVID-19 vaccines.
Further data requested
Given
the limitations of the evidence upon which the recommendations above
are derived and the anticipated continued evolution of the virus, the
TAG-CO-VAC strongly encourages generation of the following data (in
addition to the types of data outlined in October 2024):
- Immune
responses and clinical endpoints (i.e. VE and/or comparator rates of
infection and severe disease) in varied human populations who receive
COVID-19 vaccines with a monovalent JN.1 or KP.2 vaccine antigen
composition, across different vaccine platforms, as well as further
clinical and laboratory data on the performance of all currently
approved COVID-19 vaccines against emerging SARS-CoV-2 variants.
- Strengthened epidemiological and virological surveillance, as per the Standing Recommendations for COVID-19 in accordance with the International Health Regulations (2005), to determine if emerging variants are antigenically distinct and able to displace circulating variants.
- Clinical evaluation of relevant new vaccine antigens derived from more recent variants.
