In an interim Phase 1/2a study, the single-dose vaccine being developed by Janssen Pharmaceutical Companies, a subsidiary of Johnson & Johnson, provided an immune response that lasted for at least 71 days, according to a press release from Johnson & Johnson.
The study results were published in the New England Journal of Medicine. A preview of part of the trial results were posted on medRxiv in September 2020.
The company also said it anticipates announcing initial Phase 3 data for its single-dose Janssen COVID-19 vaccine candidate in late January 2021. However, as this trial is dependent on disease events, the timing is approximate.
The Phase 1/2a interim analysis showed that the company’s COVID-19 vaccine candidate (JNJ-78436735) induced an immune response and was generally well-tolerated across all study participants.
Data demonstrated that, after a single vaccination, neutralizing antibodies against COVID-19 were detected in over 90 percent of study participants at day 29 and 100 percent of participants at day 57. These neutralizing antibodies remained stable through Day 71, currently the latest time point available in the ongoing study.
The data was based on participants 18-55 years old. Johnson & Johnson said data on durability of immune responses in trial participants aged over 65 years will be available in late January.
If the single-dose vaccine is shown to be safe and effective, the company expects to submit an application for emergency use authorization (EUA) with the U.S. Food and Drug Administration shortly afterwards, with other regulatory applications around the world to be made subsequently.
The study also evaluated a two-dose regimen, in which the data showed that a second dose of the vaccine candidate, administered 56 days apart, was less reactogenic, while it triggered more than a two-fold increase in antibodies against COVID-19.
The study is ongoing at multiple clinical sites in Belgium and the United States.
The full set of results for this Phase 1/2a study will be published once the complete trial data are available.
The interim analysis also included unblinded safety data which showed that injection site (local) and systemic reactions to vaccinations either occurred on the day of immunization or the next day, and generally resolved within 24 hours. The most frequent solicited adverse events (mild-to-moderate side effects typically associated with vaccinations) in the vaccine study arms were fatigue, headache, myalgia and injection site pain. Reactogenicity was lower in the older age group. The study also evaluated a two-dose regimen, in which reactogenicity was observed to be lower after the second vaccine dose.
Five serious adverse events were reported; one participant visited the hospital for a fever that was associated with vaccination (the participant recovered within 12 hours); the remaining four were confirmed by study investigators as unrelated to the vaccine candidate.
