An FDA advisory committee on Friday voted unanimously in favour of recommending that Johnson & Johnson's single-dose COVID-19 vaccine candidate Ad26.COV2.S be granted an emergency-use authorisation (EUA) for use in people 18 years and older. The panel's backing comes days after the FDA released briefing documents in which agency reviewers said the vaccine appeared safe in clinical trials and protected against SARS-CoV-2 infection, with "high" efficacy against severe/critical illness seen across variants.
"If authorised, [our] vaccine candidate would play a pivotal role in the global effort to fight COVID-19," stated Johan Van Hoof, global head of vaccines research at Johnson & Johnson's Janssen Pharmaceutical unit, as "a single-dose regimen offers the ability to vaccinate a population faster."
If the FDA authorises Johnson & Johnson's Ad26 vector-based candidate, a decision some say could come in the days ahead, that would make it the third coronavirus vaccine to get an EUA after Pfizer and BioNTech's BNT162b2 and Moderna's mRNA-1273. Both work by using mRNA and have demonstrated roughly 95% efficacy against symptomatic disease. Johnson & Johnson's filing was supported by data from the pivotal Phase III ENSEMBLE trial showing Ad26.COV2.S had an overall efficacy rate of 66% at preventing moderate-to-severe COVID-19, four weeks after vaccination.
Effectiveness of Johnson & Johnson's vaccine also varied by region, with the level of protection against moderate-to-severe disease being 72% in the US at 28 days post-vaccination, dropping to 66% in Latin America and 57% in South Africa, where the highly transmissible B.1.3.5 strain was predominant. However, FDA staff noted that Ad26.COV2.S provided benefit "against severe/critical COVID-19 [that] was similarly high across the US, South Africa and Brazil," reducing cases of such illness by 85.9%, 81.7% and 87.6%,respectively.
FDA advisory panel members suggested that a key challenge for Johnson & Johnson's candidate will be explaining to the general public how it compares to the other vaccines. "We have a vaccine now that has good efficacy that everyone is going to compare to the existing vaccines and say it doesn't look quite as good," remarked panelist Eric Rubin. However, he said "I think it's a relatively easy call. It clearly gets way over the bar and it's nice to have a single-dose vaccine."
In their report, FDA reviewers also found "no specific safety concerns" linked to Ad26.COV2.S in the ENSEMBLE trial, although their analysis highlighted some cases of thromboembolic events, including deep vein thrombosis and pulmonary embolism, that were numerically slightly more common among vaccine recipients than for placebo, and that the agency considers these as being "of clinical interest." Meanwhile, FDA medical officer Yosefa Hefter noted there are still unknowns about the vaccine, including the duration of immune protection and the safety and effectiveness in children.
However, several advisory panel members stressed the urgency of fighting a pandemic. "We're in a race between the virus mutating, new variants coming out that can cause further disease and stopping it," commented Jay Portnoy, adding "we need to get this vaccine out. I do believe the evidence supports its safety and effectiveness."
For related analysis, see ViewPoints: Three’s a welcome crowd – J&J offers more than just one more COVID-19 vaccine.
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