J&J proposes sliding booster timelines as FDA questions lack of data for Delta, older adults before adcomm
While both Pfizer/BioNTech and Moderna are looking to administer boosters for their Covid-19 vaccines six months after the initial two-dose series, J&J — which has vaccinated about 15 million Americans so far with its one-shot vaccine — is taking a more unique approach with boosters.
According to briefing documents released ahead of Friday’s FDA adcomm on the booster dose, J&J is calling for its boosters to be administered anywhere from two months to six months following the initial shot, depending on the strength of the immune responses.
“The need for a booster dose and/or its timing will depend on the local/epidemiological situation and the needs of individuals/specific populations,” J&J said.
In FDA’s briefing document, the agency did not take a stand on whether this sliding interval for a booster would be adequate, but the agency did suggest, with caveats, there may be some benefit when a booster is administered just two months after the primary shot.
“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, when compared to the efficacy seen in the pivotal study,” the agency said.
However, confidence intervals around the efficacy estimates for a single dose vs. two doses overlap, FDA says, adding:
Additionally, the small sample size cases in individuals 60 years of age and older limits the ability to conclude about an increase in efficacy after the second dose in this group. Finally, the small number of accrued cases confirmed to be caused by the Delta variant precludes any conclusion regarding efficacy against that variant.
But on the safety end, similarly to what FDA said with Moderna, review of safety analyses following a second dose (2-month interval) among several thousand recipients with a median blinded follow-up of 36 days “do not identify increased reactogenicity or new safety concerns compared with the safety profile of the single dose; however, post-authorization surveillance will be needed to further evaluate and quantify the risk of uncommon but medically important adverse reactions.”
The FDA also made clear that the mRNA vaccines are superior in terms of efficacy to the J&J shot:
Overall, data indicate that the Janssen COVID-19 Vaccine still affords protection against severe COVID-19 disease and death in the United States, although the highest effectiveness estimates (including for more severe COVID-19 disease) across clinical trials and real-world effectiveness studies evaluating the Janssen COVID-19 Vaccine are consistently less than the highest effectiveness estimates for the mRNA COVID-19 vaccines.
FDA’s VRBPAC will meet tomorrow and Friday to discuss the safety and efficacy of the Moderna and J&J boosters.