The European Centre for Disease Prevention and Control (ECDC) and the European Medicines Agency (EMA) are providing an update on the proposed adaptation of the authorised COVID-19 vaccines and reinforcing interim public health considerations1 on the use of such vaccines during the upcoming autumn 2023 vaccination campaigns.
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The currently authorised COVID-19 vaccines in the EU/EEA include the following strain(s): bivalent Wuhan and Omicron BA.1, bivalent Wuhan and Omicron BA.4/5, monovalent Wuhan, monovalent Beta (B.1.351), and bivalent Beta (B.1.351) and Alpha (B.1.1.7).
Available effectiveness data show that currently approved COVID-19 vaccines, including those based on the index virus, continue to provide protection against severe disease.
However, protection declines as virus mutates to immunologically distant variants from strains included in the vaccines.
Members of the International Coalition of Medicines Regulatory Authorities (ICMRA) including WHO met on 8 May and the WHO Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC) met on 11-12 May and issued a statement on 18 May5,6.
In both meetings the conclusion has been that there is a need to update COVID-19 vaccine composition.
Both groups concluded that the SARSCoV-2 virus appears to evolve, diverging from the index virus.
The conclusion of these bodies has been that, while waiting for more data, monovalent XBB-containing vaccines could be considered a reasonable choice for the autumn 2023 vaccination campaign to enhance vaccine-induced immune responses to circulating SARS-CoV-2 variants based on current epidemiology and the high level of immunity already present against ancestral and previously circulating strains.
Based on surveillance and sequencing data, the XBB.1 descendent lineages currently predominate globally (i.e., XBB.1.5, XBB.1.16, XBB.1.9) including in the EU/EEA countries.
Having considered the WHO TAG advice as well as the ICMRA position statement on this matter, the EMA Emergency Task Force (ETF) is of the opinion that:
• a monovalent vaccine composition is suitable to ensure adequate immunogenicity against circulating SARS-CoV-2 in both primed and naïve individuals.
Since the ancestral strain or previous variants of concern account for an extremely small proportion of circulating strains in the EU/EEA countries, and given the high level of pre-existing immunity against them, it is not necessary to keep them in the vaccine formulation going forward;
• the inclusion of a strain belonging to the XBB family of Omicron subvariants is adequate to ensure cross-reactivity against current dominant and emerging strains, and XBB.1.5 is considered as a reasonable choice to increase the breadth of immunity also against XBB descendent lineages.
Vaccine compositions containing other XBB strains (e.g.
XBB.1.16) could be considered based on adequate justification;
• such monovalent vaccines could be used for revaccination.
They could also be used for primary vaccinations in younger children below 5 years of age, who are more likely to be naïve to the virus and never vaccinated.
This age cut off is conservatively based on epidemiological data indicating that children older than 5 years have largely been exposed to SARS-CoV-2, either by infection, vaccination, or both and therefore have already mounted an immune response specific to SARS-COV27,8;
• using a platform approach, as already experienced for adapted mRNA vaccines in 2022, is considered acceptable to approve strain change variations.
Approvals can be based on manufacturing/quality and non-clinical data only, provided the vaccine platform can demonstrate predictability of clinical immunogenicity and reactogenicity.
Such clinical data can be based on different variants of concerns9 (VOCs) that have been previously investigated.
Moreover plans for post-authorisation monitoring of effectiveness and immunogenicity/safety will have to be discussed at the time of evaluation with the Committee for Medicinal Products for Human Use (CHMP). ■