In June 2022, the TAG-CO-VAC published an interim statement highlighting that index virus-based vaccines continued to confer high levels of protection against severe disease caused by all SARS-CoV-2 Variants of Concern (VOCs), including Omicron.
However, given the antigenic distance and uncertainties of further viral evolution, the TAG-CO-VAC recognized that it was likely that the effectiveness of vaccines based on the index virus would reduce over time.
The TAG-CO-VAC therefore advised vaccine manufacturers and regulatory authorities to consider an update of vaccine antigen composition by including Omicron, as the most antigenically distinct SARS-CoV-2 variant thus far, for administration as a booster dose.
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多家疫苗制造商开发了具有经过更新的抗原成分的COVID-19疫苗；
Multiple vaccine manufacturers have developed COVID-19 vaccines with an updated antigenic composition; this includes several bivalent mRNA-based vaccines containing earlier Omicron descendent lineages, in addition to the index virus (i.e., index virus + BA.1 or BA.4/5), which have been authorized for emergency use by regulatory authorities.
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2023年3月16日至17日，COVID-19疫苗成分技术咨询小组在阿曼马斯喀特再次召开会议。
On 16-17 March 2023, the TAG-CO-VACreconvened in Muscat, Oman.
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会议的目的有两个：审查作为加强剂纳入了奥密克戎后代谱系的经过更新的COVID-19疫苗性能的证据；
The purpose of the meeting was two-fold: to review the evidence on the performance of updated COVID-19 vaccines that incorporate descendent lineages of Omicron as a booster dose; and to establish timelines for COVID-19 vaccine composition recommendations in 2023.
The evidence reviewed by the TAG-CO-VAC to assess the performance of updated COVID-19 vaccines that incorporated descendent lineages of Omicron included: (1) published observational epidemiological studies of estimates of absolute and relative vaccine effectiveness of BA.1- or BA.4/5-containing bivalent mRNA vaccines used as a booster dose against symptomatic and severe disease; (2) laboratory-based data on the magnitude and breadth of cross-reactive immune responses against previous and circulating SARS-CoV-2 variants induced by BA.1- or BA.4/5- containing mRNA vaccines, as compared to index virus-based vaccines, used as a booster dose; and (3) laboratory-based studies and observational data on immune memory responses to evaluate the impact of repeated antigen exposure on vaccine-induced immunity and protection.
Booster doses of index virus-based vaccines continue to confer high levels of protection against severe disease and death caused by all SARS-CoV-2 variants, including contemporary Omicron descendent lineages.