A syringe is prepared with the Pfizer COVID-19 vaccine at a vaccination clinic at the Keystone First Wellness Center in Chester, Pennsylvania, December 15, 2021. Matt Rourke / Associated Press
Pfizer announced on Saturday that adjusting the COVID-19 vaccine to better target the Omicron variant is safe and working – just days before regulators are considering whether to offer Americans updated booster vaccines this fall.
The vaccines currently in use in the United States still offer strong protection against severe COVID-19 disease and death – especially if people have received a booster dose. But these vaccines target the original coronavirus strain, and their effectiveness against any infection dropped significantly when the super-infectious mutant Omicron appeared.
Now with Omicron’s even more widely available relatives, the Food and Drug Administration is considering ordering a change in prescription for vaccines made by both Pfizer and rival Moderna in hopes that the modified boosters can better protect against another jump of COVID-19, expected this fall and winter.
Pfizer and its partner BioNTech have explored two different ways to update their photos – targeting Omicron only or a combination booster that adds Omicron protection to the original vaccine. They also tested whether to maintain today’s standard dose – 30 micrograms – or double the strength of the injections.
In a study of more than 1,200 middle-aged and older adults who already had three doses of the vaccine, Pfizer said both booster approaches stimulated a significant jump in Omicron-fighting antibodies.
“Based on this data, we believe we have two very strong candidates adapted to Omicron,” Pfizer CEO Albert Burla said in a statement.
Pfizer’s Omicron-only booster elicited the strongest immune response against this option.
But many experts say combination injections may be the best approach because they will retain the proven benefits of the original COVID-19 vaccine while adding new protection against Omicron. And Pfizer said that a month after people received his combined injection, they had a 9 to 11-fold increase in antibodies fighting Omicron. This is more than 1.5 times better than another dose of the original vaccine.
Importantly, preliminary laboratory studies show that the corrected images also produce antibodies capable of fighting genetically different relatives of Omicron called BA. 4 and BA. 5, although these levels were not so high.
Moderna recently announced similar test results for its combination vaccine, which scientists call a “bivalent” vaccine.
The studies are not intended to track how well updated boosters prevent COVID-19 cases. It is also not clear how long any additional protection will last.
But FDA scientific advisers will discuss the data publicly on Tuesday as they battle to recommend a change in vaccine prescriptions – before similar decisions from other countries.
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