Staff did not take a stand after reviewing the drug manufacturer’s application for booster authorization; The trick appears to be driven by insufficient data
In documents made public Tuesday, FDA employees reiterated Moderna’s request and analyzed Moderna’s study data. The additional doses of Moderna’s vaccine appeared to be safe and worked well, but employees said its benefits would depend on how much protection has waned from the primary series.
The FDA’s analysis indicates that existing Moderna data may not be enough for the panel to recommend authorizing Moderna’s boosters as widely as Pfizer, although experts cautioned that the final outcome was difficult to predict. Will happen.
“I don’t know if that’s enough of a slam dunk to begin with,” said Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine and co-director of the Texas Children’s Hospital Center for Vaccine Development.
The FDA said the data indicates that the first two doses of Moderna Vaccine still provide protection against serious illness and death.
The staff said the third dose substantially increased the antibody response, an endpoint of the study. Additional doses, however, increased antibody levels by a large magnitude and, in a high enough percentage of study subjects, missed meeting other study endpoints.
Moderna reached a different conclusion in a report submitted to the FDA. The company’s report had different figures for the second endpoint on antibody levels, and it was not immediately clear why there were discrepancies.
Moderna did not respond to a request for comment.
The FDA staff review now goes to a committee of outside experts, who are due to meet on Thursday to discuss whether the agency should authorize the Moderna booster shot. A decision is expected by the FDA after an expert panel meeting.
The Biden administration has pushed for widespread use of the booster, partly to help protect people from the infectious delta variant, as well as to counteract any weakening strength of the vaccine.
Yet many health experts have said that there is not enough evidence to support giving higher additional doses to people who have weakened immune systems due to age or medical conditions.
In August, the FDA authorized boosters from Moderna and Pfizer and partner BioNTech SE for use by the immunocompromised.
FDA employees often state, in materials sent to an advisory panel, whether a product works safely in testing for approval, while also providing any warnings or concerns. For example, in their assessment of the original vaccines from Pfizer-BioNtech and Moderna in December 2020, FDA staff described them as “highly effective” or meeting the criteria for success.
Despite the lack of support from Pfizer Booster’s staff, the agency later authorized an additional dose for seniors and some high-risk adults.
The FDA has set two conditions for the assessment of the Kovid-19 booster. One of these study endpoints was an increase in the level of neutralizing antibodies equal to or above the post-vaccination level with the first two doses. Neutralizing antibodies are immune-system agents that help fight viruses.
The second endpoint was that the percentage of subjects whose antibody levels increased fourfold after receiving the additional dose was not significantly lower than the percentage of subjects who had a fourfold increase in antibody levels after taking the primary series.
FDA staff said Moderna Booster fell statistically short of that latter measure in all study subjects, but was very close.
The staff said subjects who had low antibody levels before the booster were at least four-fold more likely to achieve a boost than those who had high antibody levels pre-booster.
According to staff reports, people younger than 65 in the study had higher baseline antibody levels than those 65 and older before receiving the booster. After the booster, the study found that a higher percentage of people 65 and older had a four-fold increase in antibody levels compared to those under 65.
FDA staff also took no stance on what the booster dose should be. Moderna has asked that the booster be half the dose used in the primary series. Both doses were studied, and the FDA review focused on lower doses.
Moderna said its clinical trials revealed no new safety indications with the booster dose and said no cases of the heart-inflammatory condition known as myocarditis were seen.
In Europe, where the vaccine is authorized for adolescents and young adults, several countries, including Finland, Sweden and Norway, are recommending against its use in young people out of concerns about a possible increased risk of a rare heart condition.
Moderna is requesting boosters for seniors and adults at risk of severe COVID-19 because of where they work. The vaccine is currently authorized for use in people 18 years of age and older.