The clinical results of phase 1/2a of the Johnson and Johnson new crown vaccine: a single vaccination stimulates antibodies and cellular immune responses.

Ad26.COV2.S is a candidate for the new crown vaccine developed by Johnson and Johnson's Janssen based on non-replica replicated adenovirus vectors.
it uses a serotype 26 adenovirus vector (Ad26) to express the pre-fusion neo-coronavirus pyrethroid protein (S protein).
in this clinical trial, adult participants aged 18-55 were divided into two groups (queue 1a and 1b) who received one or two doses of the Ad26.COV2.S vaccine, or placebo.
the trial also included a healthy group of older persons over 65 years of age (queue 3).
, published in medRxiv, looked at security data for queues 1a, 1b and 3, as well as vaccine immunogenicity data for queues 1a and 3.
safety data Ad26.COV2.S showed good safety and tolerance, with the most common adverse event (AE) being pain at the injection site.
in the adult group of 18-55 years old (queue 1a), 64 percent of the participants reported systemic adverse events, the most common reactions being fatigue, headaches, and muscle pain.
19 percent of the participants developed fever symptoms, although all fever events occurred within 2 days of vaccination and disappeared within 1-2 days.
noted that only 36 per cent of participants in the older group over the age of 65 reported systemic adverse events.
this data suggests that the vaccine candidate may cause fewer systemic adverse events in older adults than in adults.
safety data for
Ad26.COV2.S (Photo source: Reference: Reference 1) Antibody immune response In this trial, participants were vaccinated at doses of 5E10 (low dose) or 1E11 (high dose) virus particles (vp).
in the queue of 1a participants, 99 percent of the participants tested positive for the antibody serotonin of the new coronavirus S protein from yin to yang after 29 days of one vaccination.
100 percent of the participants in the group over the age of 65 had significantly higher levels of antibodies to the S protein.
using wild virus meso-testing (wtVNA), the researchers found that 92 percent of adult group participants and 11/12 of older group participants experienced serotoning of antibodies 29 days after a candidate vaccine.
researchers noted that 82 percent of the participants in The Queue 1a and 94 percent of the participants who were vaccinated against the high-dose candidate vaccine had an antibody titration of more than 100, meaning that one dose of Ad26.COV2.S was able to stimulate a strong antibody immune response in most participants.
Ad26.COV2.S stimulates antibodies (A) and mediated antibody reactions (B) against S proteins (Photo source: Reference 1) Cellular immune response Researchers note that previous preclinical studies of SARS-CoV and MERS-CoV vaccines have shown that vaccine-biased CD4-positive T-cell reactions may be associated with vaccine-related enhanced respiratory disease (virus associated with respiratory disease, VAERD).
so the researchers examined the type of CD4-positive T-cell reaction triggered by Ad26.COV2.S.
test results showed that in the adult and older groups, most of the participants produced a positive T-cell reaction that detected Th1 CD4, and only one participant in the adult group developed a detectable Th2-type CD4-positive T-cell reaction.
the participant, the Th1/Th2 response ratio was 28.9, indicating that CD4-positive T-cell reactions tended to Th1.
Ad26.COV2.S-stimulated CD4-positive T-cell reaction (Photo source: Reference 1) At the same time, the researchers also found that the S-protein-specific CD8-positive T-cell reaction was detected in both the adult and older groups 15 days after one vaccination.
in the discussion of the article, the researchers noted that a strong CD4-positive Th1 immune response, combined with CD8-positive T-cell reactions and antibody reactions, minimizes the theoretical risk of vaccine-related respiratory diseases.
discussions, the researchers noted that current data do not yet determine the durability of the immune response triggered by the Ad26.COV2.S vaccine candidate.
in previous studies based on the same vector-based Zika virus vaccine, a dose of the vaccine allowed 56 percent of inoculators to remain serotype-positive for at least 12 months.
, however, the durability of immunity is not only related to the maintenance of neutral antibody levels, but also to the degree to which vaccines stimulate immune memory.
immune memory refers to the immune system's immune response to vaccines that causes memory B cells and memory T cells that recognize new coronavirus-specific antigens to remain in the bone marrow and produce neutral antibodies and T-cell reactions more quickly when the virus invades again.
in this regard, the researchers will use very low doses of the candidate virus vaccine in Phase 2a clinical trials to simulate new coronavirus infections and test the immune memory response of vaccinated participants.
immunogenic response based on low-dose and high-dose candidate vaccines is comparable, the researchers will use a low dose of 5E10 vp for further study in subsequent trials.
: s1. Sadoff, et al., (2020). Safety and immunogenicity of the Ad26.COV2.S COVID-19 vaccine candidate: in resultterims of a phase 1/2a, double-blind, randomized, placebo-controlled trial. medRxiv,