There isn’t enough data to recommend COVID-19 booster jabs for Omicron subvariants over the original virus, the World Health Organization’s (WHO’s) panel of vaccine experts said on Tuesday.
Four variant-containing mRNA vaccines that either include bivalent Omicron subvariants BA.1 or BA.4–5 in combination with the “ancestral virus” have been authorized for use as booster doses. The Strategic Advisory Group of Experts on Immunization (SAGE) said in a statement that it reviewed the “safety and immunogenicity” of bivalent vaccines when given as a booster in adults compared to the results of a clinical trial from another kind of vaccine.
Bivalent vaccines are designed to target two different strains of the virus. They contain both the mRNA of the original virus strain and that of the Omicron variant, which accounts for almost all virus samples collected in the last 30 days. The bivalent jabs targeting the dominant subvariant might only offer a “minute incremental benefit,” according to SAGE, which determined that the highest public health priority is to achieve high rates of a primary dose of vaccine containing the “ancestral strain” of the virus.