Unclear which combination of updated vaccine will work best; body expected to decide by July
Vaccines against COVID-19 should be updated to incorporate the omicron variant of the virus dominating the world, according to the advisory panel of the United States’ Food and Drug Administration (FDA).
Only two of the 21 members of the Vaccines and Related Biological Products Advisory Committee voted ‘no’, citing lack of data, in answer to the question: Does the committee recommend inclusion of a SARS-CoV-2 omicron component for COVID-19 booster vaccines in the US?
FDA is expected to make a decision about the combination of the updated vaccine in July.
The decision will impact vaccine manufacturers, many of whom announced a variant-specific vaccine in the making. Pfizer Inc and BioNTech had stated on June 25, 2022 their omicron-specific monovalent dose triggered a “substantially higher immune response against omicron BA.1 as compared to the companies’ current COVID-19 vaccine.”
Moderna Inc had stated June 8, 2022 that its bivalent vaccine elicited a “superior neutralising antibody response”. Both of these shots provide protection against BA.4 and BA.5, though to a lesser extent as compared to BA.1.
The newest sub-lineages make up more than half the cases in US and are on the rise in other parts of the world as well. Portugal and South Africa have already declared the dominance of BA.5 and experts believe it’s likely other countries will follow suit. BA.5 is particularly concerning because it has the strongest immunity-evading characteristics.
This raises the question: Which combination of the updated vaccine would work best? Should the updated vaccine focus on BA.1 or those sub-lineages on the rise now — BA.4 and BA.5? The body debated for a whole day but it remains unclear what the path forward will be.
However, experts were largely leaning in favour of a monovalent booster shot targeting BA.4 and BA.5 as well as a bivalent primary vaccine constituting the original ‘Wuhan strain’ and omicron.
This school of thought is different from what the World Health Organization’s (WHO) Technical Advisory Group on COVID-19 Vaccine Composition said in its interim statement on June 17. It noted:
Available data 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.
It’s a difficult balance to strike but experts believe an omicron-specific vaccine would not be so effective anymore since the variant has already been replaced by its sub-lineages since they have a significant growth advantage over it.
Other concerns include whether vaccine manufacturers can keep up with how quickly the SARS-CoV-2 virus is mutating — five variants of concerns have already emerged with omicron’s sub-lineages now becoming dominant.
“This is actually one of the more challenging scientific and scientifically nuanced decisions that FDA has to make because, in a sense, we are trying to predict the future based on probability and odds and the best scientific data that we have, knowing full well that this virus has surprised us previously,” Marks, director of FDA’s Centre for Biologics Evaluation and Research, was quoted as saying by STAT, a health website.
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