- Pfizer and BioNTech on Thursday said their updated COVID-19 booster spurred higher levels of antibodies against the omicron variant among adults enrolled in a clinical trial, six weeks after the reformulated shot was first cleared by the Food and Drug Administration.
- The findings, which the companies described in a press release without sharing specific data, are the first immune response results for the booster, which is adapted to the BA.4 and BA.5 substains of omicron. Pfizer and BioNTech previously relied on similar results for a booster aimed at the BA.1 substrain, as well as preclinical data for the BA.4/5 shot.
- According to the companies, a dose of the bivalent shot led to a “substantial increase” in neutralizing omicron antibodies compared to pre-booster levels. Among adults over the age of 55 who received either the original booster or the reformulated shot, the original version resulted in “more limited increases” of antibodies against the omicron BA.4 and BA.5 strains.
Pfizer and BioNTech, as well as the FDA, have moved quickly to make boosters updated for the omicron available, concerned that waning immunity may leave people vulnerable. Their speed has meant the FDA’s authorizations, first in August for adults and then this week for younger children, have been based on more limited information than previously.
The FDA’s initial decision was supported by data from clinical trials run by the company of an earlier booster containing messenger RNA for both the original coronavirus strain and the BA.1 omicron variant. But the FDA favored a shot targeted to the more widely prevalent BA.4 and BA.5 strains, which Pfizer and BioNTech had to scramble to make ready.
Their view, and the view of the agency, was the boosters were so similar that data from the first could be used to support consideration of the second, along with preclinical laboratory data and manufacturing information.
While the FDA authorized the newer omicron booster for adults and children over 12 years old in late August, the agency only cleared it for kids between the ages of 5 and 11 on Wednesday. The Centers for Disease Control and Prevention quickly followed with a formal recommendation.
But the data still don’t answer questions of exactly how well the boosters will protect people from infection, hospitalization and death, as the larger vaccine effectiveness studies needed to find that out haven’t been run. The FDA relies on immune response and manufacturing data to clear vaccines for other diseases, provided they’re well understood.
The “substantial increase” in antibody levels cited by Pfizer and BioNTech in their statement was measured seven days after study participants received the updated booster. The study was relatively small, with only 40 participants in each age group of 18 to 55 and older than 55 years old.
However, Pfizer and BioNTech said that additional data from one month follow-up is expected sometime in the next few weeks, which will give a better sense of how well the booster shot raises antibody levels. The new data will also be used by the companies to ask for full approval of the updated shot.
Since the FDA’s clearance in August, uptake of the booster has been slow. So far, only 11.5 million people have received the updated booster, according to data from the CDC.
While COVID-19 cases have declined since September, health officials worry about an upcoming surge in cases as the weather gets colder and flu season takes hold. Children in school are of particular concern, with only about a third of children between the ages of 5 and 11 having completed the two-dose vaccination. Even fewer children between six months and 4 years have received two doses of a COVID-19 vaccine.