Interim statement on the composition of current COVID-19 vaccines

Key messages: The primary goals of COVID-19 vaccination using currently licensed vaccines continue to be to reduce hospitalization, severe disease and death, and to protect health systems. The use of currently licensed vaccines based on the index virus (i.e. the virus that was identified from the first cases of COVID-19 in December 2019) confers high levels of protection against severe disease outcomes for all variants, including Omicron with a booster dose. There has been continuous and substantial virus evolution since SARS-CoV-2 emerged in late 2019 and it is likely that this evolution will continue, resulting in the emergence of new variants, particularly those with changes in the spike protein. The trajectory of SARS-CoV-2 evolution remains uncertain and the genetic and antigenic characteristics of future variants cannot yet be predicted. Given the uncertainties of further evolution, it may be prudent to pursue an additional objective of COVID-19 vaccination of achieving broader immunity against circulating and emerging variants while retaining protection against severe disease and death. Available data (see Annex) indicate that the inclusion of Omicron, as the most antigenically distinct SARS-CoV-2 Variant of Concern, in an updated vaccine composition may be beneficial if administered as a booster dose to those who have already received a COVID-19 vaccination primary series. The Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC) is an independent group of experts that has continued to assess the public health implications of emerging SARS-CoV-2 Variants of Concern (VOC) on the performance of COVID-19 vaccines in order to issue timely recommendations on potential modifications to vaccine strain composition. Since the designation of the Omicron VOC by the World Health Organization (WHO) in November 2021, the TAG-CO-VAC has closely followed the impact of Omicron on the performance of currently licensed COVID-19 vaccines to consider whether a change in COVID-19 vaccine composition may be warranted­­­. Further to the interim statement published on 8 March 2022, this TAG-CO-VAC statement is intended to offer Member States, vaccine developers and regulatory authorities considerations as to whether a modified vaccine composition may be warranted and, if so, how this may be achieved to fulfil the public health objectives of COVID-19 vaccination. Is a modified COVID-19 vaccine composition warranted? Since the classification of Omicron as a VOC, there has been rapid and relatively synchronous displacement of other circulating variants by Omicron that has caused substantial epidemic waves in all 6 WHO regions. Omicron is characterized by a large number of mutations, including many in antigenically important regions of the...