Scientists at the United States Food and Drug Administration said on Wednesday that they did not receive enough data in time to conduct their own analysis of Johnson & Johnson’s application for a booster dose of its COVID-19 vaccine, but the agency’s review of company studies raised some red flags.
The FDA’s advisory committee will meet on Oct. 15 to weigh the risks and benefits of a booster shot of J&J’s vaccine, which is currently administered as a single dose.
In their review, FDA scientists repeatedly emphasised the limitations of many of the company’s studies, such as their small sample sizes.
They noted that the data J&J used to support administering a booster shot six months after the initial shot relied on an unvalidated immune response test that was possibly not sensitive enough.
Because of the mismatch in assessment tools, meaningful comparisons with data from the company’s larger two-dose booster trial would be difficult.
Agency scientists also noted that there were insufficient cases of COVID-19 caused by the Delta variant to estimate how effective the vaccine is against the coronavirus mutation now dominant globally in that larger J&J trial evaluating two doses of the vaccine given nearly two months apart.
U.S. health officials have been under pressure to offer advice on booster doses of the J&J and Moderna COVID-19 vaccines after the White House announced in August it planned to roll out boosters beginning last month for most adults, pending approvals from the FDA and the U.S. Centers for Disease Control and Prevention (CDC).
The FDA and CDC last month signed off on boosters of the Pfizer Inc and BioNTech SE COVID-19 vaccine for certain high-risk adults, but reviews of the Moderna and J&J shots were delayed until the companies could produce more data.