PRELIMINARY data from the World Health Organization (WHO) Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC) shows that the mutational profile of the Omicron strain reduces vaccine effectiveness in symptomatic patients.
By Michael Gwarisa
The technical advisory team also called for the urgent development of COVID-19 vaccines that have high impact on prevention of infection and transmission, in addition to the prevention of severe disease and death, are needed and should be developed so as to reduce the need for booster doses.
Until such vaccines are available, and as the SARS-CoV-2 virus evolves, the composition of current COVID-19 vaccines may need to be updated, to ensure that COVID-19 vaccines continue to provide WHO-recommended levels of protection against infection and disease by VOCs, including Omicron and future variants,” said the advisory team in an interim statement.
““For the Omicron variant, the mutational profile and preliminary data indicate that vaccine effectiveness will be reduced against symptomatic disease caused by the Omicron variant, but protection against severe disease is more likely to be preserved. However, more data on vaccine effectiveness, particularly against hospitalization, severe disease, and death are needed, including for each vaccine platform and for various vaccine dosing and product regimens.”
Since the emergence of the SARS-CoV-2 virus, numerous mutations have been reported, forcing health experts across the globe to constantly change their strategies in fighting the virus. To date WHO has designated five variants as SARS-CoV-2 Variants of Concern (VOC) to namely Alpha, Beta, Gamma, Delta and Omicron – due to their impact on transmission, disease severity, or capacity for immune escape.
“While the Omicron variant is spreading rapidly across the world, the evolution of SARS-CoV-2 is expected to continue and Omicron is unlikely to be the last VOC. The TAG-CO-VAC will consider a change in vaccine composition to ensure that vaccines continue to meet the criteria established in WHO’s Target Product Profile for COVID-19 vaccines, including protection against severe disease, to improve vaccine-induced protection, to that aim, COVID-19 vaccines need to and be based on strains that are genetically and antigenically close to the circulating SARS-CoV-2 variant(s).”
In addition to protection against severe disease and death, TAG-CO-VAC said vaccines must be more effective in protection against infection thus lowering community trans- mission and the need for stringent and broad-reaching public health and social measures, elicit immune responses that are broad, strong, and long-lasting in order to reduce the need for successive booster doses.
“In line with this approach, there are many options to consider a monovalent vaccine that elicits an immune response against the predominant circulating variant(s), although this option faces the challenge of the rapid emergence of SARS-CoV-2 variants and the time needed to develop a modified or new vaccine; a multivalent vaccine containing antigens from different SARS-CoV-2 VOCs; a pan SARS-CoV-2 vaccine: a more sustainable long-term option that would effectively be variant-proof.”
Meanwhile, the TAG-CO-VAC has told COVID-19 vaccine manufacturers to generate and provide data on performance of current and Omicron-specific COVID-19 vaccines, including the breadth, magnitude, and durability of humoral and cell mediated immune responses to variants through monovalent and/or multivalent vaccines.
In September 2021, WHO established the Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC). This multidisciplinary group of 18 experts reviews and assesses the public health implications of emerging VOCs on the performance of COVID-19 vaccines and provides recommendations on COVID-19 vaccine composition. The work of this group complements that of the Technical Advisory Group on SARS-CoV-2 Virus Evolution (TAG-VE), the Strategic Advisory Group of Experts on Immunization (SAGE) and its Working Group on COVID-19 Vaccines, and the working groups of the WHO R&D Blueprint for Epidemics.
