A panel of independent experts that advises the US Food and Drug Administration on its vaccine decisions voted unanimously Thursday to update all Covid-19 vaccines so they contain the same ingredients as the two-strain shots that are now used as booster doses.
The vote means young children and others who haven’t been vaccinated may soon be eligible to receive two-strain vaccines that more closely match the circulating viruses as their primary series.
The FDA must sign off on the committee’s recommendation, which it is likely to do, before it goes into effect.
Currently, the US offers two types of Covid-19 vaccines. The first shots people get – also called the primary series – contain a single set of instructions that teach the immune system to fight off the original version of the virus, which emerged in 2019.
This index strain is no longer circulating. It was overrun months ago by an ever-evolving parade of new variants.
Last year, in consultation with its advisers, the FDA decided that it was time to update the vaccines. These two-strain, or bivalent, shots contain two sets of instructions; one set reminds the immune system about the original version of the coronavirus, and the second set teaches the immune system to recognize and fight off Omicron’s BA.4 and BA.5 subvariants, which emerged in the US last year.
People who have had their primary series – nearly 70% of all Americans – were advised to get the new two-strain booster late last year in an effort to upgrade their protection against the latest variants.
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