A new FDA analysis questioned the strength of evidence Johnson & Johnson provided in its application for booster shot approval.
As reported by the New York Times, a key test the company used was likely not sensitive enough, the FDA suggested, adding that it didn’t have enough time to independently review much of the raw data from the trials.
The FDA said that the test used to measure the immune response of a six-month-boost — known as a psVNA assay — is not sensitive enough for the task. The agency also questioned whether the increase in immune response was as big as the data suggested.
“It is likely that the results seen are due to the low sensitivity of the psVNA assay used,” the FDA said in its report. Regulators warned that it was difficult to compare results from the company’s six-month and two-month booster studies as a result.
The FDA saw a potential improvement in protection from a J&J booster given two months after the first shot, based on a large trial sponsored by the company.
“Although not independently confirmed by FDA from datasets, summaries of the data suggest there may be a benefit in a second dose administered approximately 2 months after the primary dose,” the agency said in its report.
The document could impact whether the 15 million people who got the one-dose J&J vaccine will be able to get a second shot, or if they will have to move to a different brand.