Pfizer announced Saturday that adjusting its COVID-19 vaccine to better target the omicron variant is safe and effective, just days before regulators debate whether to offer updated booster shots to Americans this fall.
Vaccines currently used in the United States still offer strong protection against severe COVID-19 illness and death, especially if people have received a booster dose.
But those vaccines target the original strain of the coronavirus, and their effectiveness against any infection dropped sharply when the more contagious omicron variant emerged.
Now that omicron’s even more transmissible relatives have spread widely, the Food and Drug Administration (FDA) is considering ordering a prescription change for vaccines made by Pfizer and its rival Moderna, hoping that the modified boosters can better protect against another wave of COVID-19 expected this fall and winter.
Pfizer and its partner BioNTech studied two different ways to upgrade their vaccines: target omicron alone, or a booster combination that adds omicron’s protection to the original vaccine.
In addition, they discussed whether to maintain the current 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 had already received three doses of the vaccine, Pfizer said that both booster methods caused a substantial increase in antibodies that fight the omicron variant.
“From these data, we believe we have two very strong omicron-matched candidates,” Pfizer CEO Albert Bourla said in a statement.
Pfizer’s booster against omicron elicited the strongest immune response against that variant.
However, many experts say that the combination of vaccines could be the best approach, as it would retain the proven benefits of the original COVID-19 vaccine and add new protection against the omicron variant.
Pfizer added that a month after people receive their combination vaccine they have a 9- to 11-fold increase in antibodies that fight omicron.
And, importantly, preliminary laboratory studies show that the modified vaccines also produce antibodies capable of fighting off genetically distinct relatives of omicron, called BA.4 and BA.5, even though their levels were not as high. elevated.
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