Interim Statement on COVID-19 vaccines in the context of the circulation of the Omicron SARS-CoV-2 Variant from the WHO Technical Advisory Group on…

Key messages:

The World Health Organization, with the support of the Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC),continues to review and assess the public health implications of emerging SARS-CoV-2 Variants of Concern (VOC) on the performance of COVID-19 vaccines. Since the publication of the interim statement on COVID-19 vaccines on 11 January 2022, Omicron has become the dominant VOC globally,rapidly replacing other circulating variants. This statement highlights the global epidemiological situation, challenges of updating vaccine composition and provides the current position of the TAG-CO-VAC.

The current global epidemiological situation is characterized by rapid and relatively synchronous dominance of Omicron variant in all six WHO regions. While global cases are declining, there are reduced testing resources and capacities in some areas andthe epidemiological situation remains heterogeneous, with a number of regions and countries reporting increases in new weekly cases, while others are now reporting declines.

Omicron is comprised of several genetically related sublineages, including BA.1, BA.2 and BA.3, each of which is being monitored by WHO and partners. At a global level, BA.1 has been the predominant Omicron lineage, however, the proportion of reportedsequences designated as BA.2 has been increasing relative to BA.1 in recent weeks, and is the predominant Omicron lineage in several countries. BA.1 and BA.2 have some genetic differences, which may make them antigenically distinct. Reinfection withBA.2 following infection with BA.1 has been documented, however, initial data from population-level studies suggest that infection with BA.1 provides substantial protection against reinfection with BA.2, at least for the limited period for which dataare available. For more details on the Omicron sublineages, please refer to the statement by WHO on the Omicron sublineage BA.2 , published on 22 February 2022.

The public health goal of COVID-19 vaccination prioritizes protection against severe disease and death. Current vaccines appear to confer high levels of protection against severe disease outcomes associated with Omicron infection. The TAG-CO-VAC thereforestrongly supports urgent and broad access to current COVID-19 vaccines for primary series and booster doses, particularly for groups at risk of developing severe disease. The near- and medium-term supply of the available vaccines has increased substantially,however, vaccine equity remains an important challenge and all efforts to address such inequities are strongly encouraged.

The first interim statement from the TAG-CO-VAC highlighted the need for the development of vaccines that provide protection against infection and prevent transmission, in addition to the protection from severe disease and death, as a means to achievea greater public health impact from COVID-19 vaccination. In this context, vaccines that are able to elicit mucosal immunity, in addition to systemic immunity, are an important goal. One of the options proposed in the first statement was the developmentof pan SARS-CoV-2 or pansarbecovirus vaccines. Such vaccines would provide protection that would effectively be variant-proof, and work in this area should be accelerated.

Current vaccines are based on the virus that circulated early in the pandemic (ancestral virus e.g. GISAID: hCoV-19/Wuhan/WIV04/2019). Since then, there has been continuous and substantial virus evolution and it is likely that this evolution will continue,resulting in the emergence of new variants. The composition of current COVID-19 vaccines may therefore need to be updated. Any update to current COVID-19 vaccine composition would aim to, at a minimum, retain protection against severe disease anddeath, while ensuring the breadth of the immune response against circulating and emerging variants, which may be antigenically distinct.

The TAG-CO-VAC considered a number of issues, all of which are important in any decision on COVID-19 vaccine composition:

The TAG-CO-VAC welcomes, where feasible, the development and initiation of clinical trials on variant-specific candidate vaccines against WHO-designated VOCs, including Omicron. In this context, the TAG-CO-VAC is seeking evidence of robust homologousimmune responses in primed and unprimed individuals and cross-reactivity data in primed individuals. The TAG-CO-VAC encourages collection of data following one and two doses of any modified vaccine across a variety of relevant vaccine platforms.

The TAG-CO-VAC continues to encourage COVID-19 vaccine manufacturers to generate and provide data to WHO on the performance of current and variant-specific candidate COVID-19 vaccines, including the breadth, magnitude, and durability of humoral and cell-mediatedimmune responses to variants through monovalent and/or multivalent vaccines. The TAG-CO-VAC will carefully consider these data as part of a broader decision-making framework on COVID-19 vaccine composition, allowing the TAG-CO-VAC to issue more specificadvice on any adjustments that may be needed to COVID-19 vaccine strain composition, developed either as a monovalent vaccine targeting the predominant circulating variant(s) or a multivalent vaccine derived from different variants.

The TAG-CO-VAC recognizes the independent role and procedures of relevant regulatory authorities in establishing the necessary requirements for evaluation under the currently established regulatory pathways, and the role of WHO in ensuring alignment,collaboration and a continuous exchange of information between WHO and its expert groups, the TAG-CO-VAC, regulatory authorities, and COVID-19 vaccine manufacturers.

The statement reflects the current vaccine performance and landscape of vaccine development. The statement will therefore be updated as data become available.

Follow this link:

Interim Statement on COVID-19 vaccines in the context of the circulation of the Omicron SARS-CoV-2 Variant from the WHO Technical Advisory Group on...