Pfizer Says Tweaked COVID Vaccines Boost Omicron Protection
Pfizer announced Saturday that tweaking its COVID-19 vaccine to better target the omicron variant is safe and works — just days before regulators debate whether to offer Americans updated booster shots this fall.
The vaccines currently used in the U.S. still offer strong protection against severe COVID-19 disease and death — especially if people have gotten a booster dose. These vaccines are only effective against the coronavirus strain, and they were significantly less effective when super-contagious Omicron mutations emerged.
Now with omicron’s even more transmissible relatives spreading widely, the Food and Drug Administration is considering ordering a recipe change for the vaccines made by both Pfizer and rival Moderna in hopes that modified boosters could better protect against another COVID-19 surge expected this fall and winter.
Pfizer and its partner BioNTech studied two different ways of updating their shots — targeting just omicron, or a combination booster that adds omicron protection to the original vaccine. They also tested whether to keep today’s standard dosage — 30 micrograms — or to double the shots’ strength.
In a study of more than 1,200 middle-aged and older adults who’d already had three vaccine doses, Pfizer said both booster approaches spurred a substantial jump in omicron-fighting antibodies.
“Based on these data, we believe we have two very strong omicron-adapted candidates,” Pfizer CEO Albert Bourla said in a statement.
Pfizer’s omicron-only booster sparked the strongest immune response against that variant.
Many experts believe combination shots might be best because they preserve the proven benefits from the COVID-19 vaccine and provide new protection against omicron. Pfizer claimed that people receiving the combination shot saw a 9- to 11-fold improvement in their anti-omicron antibodies one month after they received it. That’s more than 1.5 times better than another dose of the original vaccine.
And importantly, preliminary lab studies show the tweaked shots also produce antibodies capable of fighting omicron’s genetically distinct relatives named BA.4 and BA.5, although those levels weren’t nearly as high.
Moderna recently announced similar results from tests of its combination shot, what scientists call a “bivalent” vaccine.
The studies weren’t designed to track how well updated boosters prevented COVID-19 cases. It is not clear for how long the added protection will last.
But the FDA’s scientific advisers will publicly debate the data on Tuesday, as they grapple with whether to recommend a change to the vaccines’ recipes — ahead of similar decisions by other countries.
Read More From Time