Pfizer announced on Saturday that modifying 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.
Vaccines currently in use in the United States still offer strong protection against severe COVID-19 illness and death, particularly if people have received a booster dose. But these vaccines target the original strain of coronavirus, and their effectiveness against any infection dropped markedly when the super-contagious omicron mutant emerged.
Now that omicron’s even more transmissible relatives are spreading widely, the Food and Drug Administration is considering ordering a recipe change for vaccines made by both Pfizer and rival Moderna in hopes the modified boosters might better protect. against another surge of COVID-19 expected this fall and winter. .
Pfizer and its partner BioNTech have studied two different ways to update their vaccines – targeting only the omicron or a combined booster that adds protection against the omicron to the original vaccine. They also tested whether to keep 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 both booster approaches caused a substantial increase in anti-omicron antibodies.
“Based on this data, we believe we have two very good candidates suitable for omicron,” Pfizer CEO Albert Bourla said in a statement.
Pfizer’s only omicron booster elicited the strongest immune response against this variant.
But many experts say combination shots might be the best approach because they would retain the proven benefits of the original COVID-19 vaccine while adding new protection against omicron. And Pfizer said that a month after people got its combination shot, they had a 9- to 11-fold increase in anti-omicron antibodies. That’s more than 1.5 times better than another dose of the original vaccine.
Importantly, preliminary lab studies show that the modified injections also produce antibodies capable of fighting omicron’s genetically distinct relatives named BA.4 and BA.5, although these levels are not as high.
Moderna recently announced similar results from testing its combination vaccine, what scientists call a “bivalent” vaccine.
The studies were not designed to track how well updated reminders prevented COVID-19 cases. It’s also unclear how long additional protection would last.
But the FDA’s scientific advisers will publicly debate the data on Tuesday, as they debate whether to recommend a change in vaccine recipes — ahead of similar decisions from other countries.
The Associated Press Health and Science Department is supported by the Howard Hughes Medical Institute Department of Science Education. The AP is solely responsible for all content.