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.
“[C]urrently available data are not sufficient to support the issuance of any preferential recommendation for bivalent variant-containing vaccine boosters over ancestral-virus-only boosters,” SAGE added.
Either a monovalent jab designed for the original strain or a bivalent variant-containing shot can be used as boosters, according to the WHO panel.
The WHO panel said these shots given as boosters four to six months after the last dose provide “improved protection against currently circulating SARS-CoV-2.”
“The bulk of the benefit is from the provision of in particular the first booster dose, irrespective of whether it is a monovalent or bivalent vaccine,” SAGE said.
‘Modest Effect’ Only Seen in Labs, Not Clinical Settings
The variant-containing vaccines neutralize the virus to the same extent as ancestral shots but have a “slightly superior neutralization of the Omicron variant, according to SAGE Executive Secretary Joachim Hombach.
“It’s a relatively modest effect which we can see in the laboratory,” he said, adding that they cannot “relate these laboratory measures with an increase in clinical protection” because there’s no data on effectiveness.
via zerohedge