Among the multiple vaccine candidates around the globe, next up in the arsenal against COVID-19 is likely the single-dose Ad26.COV2.S vaccine in development from Johnson & Johnson/Janssen, infectious disease experts predict.
And it got closer with promising interim phase 1/2a trial results, published online Jan. 13 in The New England Journal of Medicine.
A single Ad26.COV2.S dose was associated with S-binding and neutralizing antibodies in more than 90% of the participants. The finding was observed in both adults aged 18-55 years and participants 65 and older, as well as for participants given low-dose or high-dose vaccinations.
The results also suggest a durable vaccine response. “The take-home message [includes] a high neutralizing antibody responder rate to a single dose of our Ad26.COV2.S COVID-19 vaccine candidate. In addition, we see that these responses and antibody titers are stable for at least 71 days,” senior study author Hanneke Schuitemaker, PhD, global head of viral vaccine discovery and translational medicine at Johnson & Johnson in Leiden, the Netherlands, said in an interview.
If the single-dose Johnson & Johnson product gains Food and Drug Administration emergency use authorization (EUA), it could significantly boost the number of overall immunizations available. Less stringent storage requirements – only regular refrigeration vs. a need to freeze the Pfizer/BioNTech and Moderna COVID-19 vaccines – is another potential advantage. The Ad26.COV2.S vaccine can be refrigerated for up to 3 months at 36°-46 °F (2°-8 °C).
“Phase 1-2 trial data on the J&J vaccine: If it works as well as the mRNA options, it will have substantial advantages,” Jeremy Faust, MD, an emergency room physician affiliated with Brigham & Women’s Hospital and Harvard Medical School, Boston, tweeted on Jan. 13.
Unlike the Pfizer/BioNTech and Moderna messenger RNA vaccines, the Johnson & Johnson product is a recombinant, replication-incompetent adenovirus serotype 26 (Ad26) vector encoding a full-length and stabilized SARS-CoV-2 spike (S) protein.
Phase 3 efficacy/safety results pending
Under normal circumstances, phase 3 trial results would not be anticipated within weeks of phase 1/2a trial findings. However, the urgency of the COVID-19 pandemic accelerated the vaccine development process, so preclinical trials were conducted simultaneously and not sequentially. For this reason, phase 3 interim results for the Johnson & Johnson vaccine are expected within weeks, and a company executive told Reuters that the rollout is on track for March.
“We hope to report data from our first phase 3 study, ENSEMBLE, in which we are testing the protective efficacy of a single dose of Ad26.COV2.S, by the end of this month or early February,” Dr. Schuitemaker said.
In the meantime, the phase 1/2a ongoing, multicenter, randomized, double-blind, and placebo-controlled trial interim results have drawn positive reactions.
“Data is highly encouraging and supports the single inoculation approach that makes this vaccine unique,” Carlos del Rio, executive associate dean for Emory University at Grady in Atlanta, wrote in a tweet on Jan. 13.
“Encouraging COVID vaccine data from J&J published [Jan. 13]. Solid antibody, CD4 T cell, and CD8 T cell responses – a nice trifecta of vaccine immune responses to see! And safe!” tweeted Shane Crotty, PhD, vaccine scientist and professor at the La Jolla (Calif.) Institute for Immunology.