Interim analysis of the J&J COVID-19 vaccine candidate (JNJ-78436735) in the ongoing Phase 1/2a clinical trial has shown that a single dose induced a strong neutralizing antibody response in almost all participants aged 18 years and older and was generally well-tolerated. The triggered immune responses were similar across all the studied age groups, including older adults.
A single dose of the J&J COVID-19 vaccine candidate induced a strong neutralizing antibody response
The results from the Phase 1/2a First-in-Human trial, published on Friday, support further clinical development of Janssen’s investigational vaccine candidate JNJ-78436735 (also known as Ad26.COV2.S). The ongoing Phase 1/2a clinical trial is intended to investigate the safety and immunogenicity of the two dose levels of the vaccine, as well as single and two-dose dose schedules.
J&J observed that the data is consistent with preclinical research, which demonstrated that a single dose of the vaccine prevented subsequent infection and provided total protection for the lungs of non-human primates.
In 99 percent of the trial participants aged 18-55 years, the production of detectable antibodies was observed. The results showed that 98% of participants were positive for the neutralizing antibodies against SARS-CoV-2 on the 29th day following vaccination.
60,000 volunteers to participate in Phase 3 COVID-19 vaccine trial
Based on the interim results, J&J launched a large-scale, pivotal, multi-country Phase 3 trial (ENSEMBLE) of its COVID-19 vaccine candidate developed by Janssen, which aims to recruit up to 60,000 volunteers across three continents. Later this year, Johnson & Johnson also intends to run a Phase 3 clinical trial of a two-dose regimen of JNJ-78436735 versus placebo.
The Janssen Vaccine Immune Response & Safety Data
The Janssen COVID-19 vaccine candidate JNJ-78436735 triggered strong antibody responses, strong T cell responses, and a Th1 response, thought to be protective against the risk of vaccine-associated enhanced respiratory disease.
Immunogenicity (the ability to trigger an immune response) data from participants aged 65 years of age and above were available for the first 15 participants, with strong humoral and cellular immune responses elicited in all elderly participants who received a single dose of the COVID-19 vaccine candidate.
Safety data from the Phase 1/2a trial identified that most of the reported adverse events were mild to moderate in severity and commonly occurred on the day of vaccination with symptoms generally resolving by the same or the next day. Two serious adverse events were reported, the first for hypotension which the investigator determined not to be vaccine-related, and the second was a participant with fever who was hospitalized due to suspicion of contracting COVID-19 but recovered within 12 hours. No life-threatening adverse events were reported in any cohort.
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