Five weeks after the first dose, the Italian vaccine GRAd-COV2 against covid-19 is effective: it has been found an antibody response against the Spike protein in over 93% of the volunteers. 99% is reached after the second administration. The level of antibodies that bind the Spike protein and neutralize the virus is comparable to that measured in a reference group of patients recovering from COVID-19 infection. This is what emerges from the results of the preliminary analysis of the phase 2 clinical trial - randomized, double-blind and placebo-controlled - conducted on the Italian adenoviral vector vaccine GRAd-COV2, developed by the biotech company ReiThera.
After the first five weeks of vaccination, the results confirm what was already observed in Phase 1: the Italian vaccine is well tolerated at the first administration and even better tolerated at the second. Adverse events, mostly mild to moderate and of short duration, are mainly related to pain and tension at the injection site, fatigue, muscle aches and headaches. There were no serious vaccine-related adverse events.
Review of preliminary data
To review the preliminary safety and immunogenicity data from the first five weeks of the study at a joint meeting on Data Safety Monitoring Board, Independent Committee for the Evaluation of Safety, and the Steering Committee, Scientific Committee for the Evaluation of Efficacy. Both committees expressed themselves favourably on the data analysed and recommended to continue the clinical development of the Italian GRAd-COV2 vaccine.
"We are very satisfied of the preliminary results of the Phase 2 COVITAR study, for which we thank the volunteers and the 24 trial centres - declared Dr. Roberto Camerini, Medical Director of ReiThera - Our vaccine confirmed the excellent safety and immunogenicity profile in a large sample of volunteers. ReiThera reaffirms its commitment to the fight against the SARS-CoV-2 pandemic to meet the global demand for vaccines. The Phase 3 program, based on a non-inferiority design with a primary immunological end-point in comparison to an already commercialized viral vector vaccine, has received a positive opinion from important regulatory agencies including the EMA and we hope to be able to start it as soon as before".
The trial began last March 18 in 24 clinical centers distributed throughout the Italian territory, was conducted on 917 volunteers of which the 25% over the age of 65 and / or with conditions associated with an increased risk of severe disease in case of SARS-CoV-2 infection. Adverse events, mostly mild to moderate and of short duration, are mainly attributable to pain and tension at the injection site, fatigue, muscle aches and headaches, the note reads. There were no serious vaccine-related adverse events.
GRAd-COV2: how does it work?
GRAd-COV2, the Italian vaccine candidate against SARS-CoV-2 recently developed by ReiThera, is based on an adenoviral vector (called GRAd), derived from monkeys (gorillas) and modified so that it cannot replicate. This vector, patented by ReiThera, encodes the entire Spike protein, which allows the new coronavirus to enter human cells. Monkey-derived adenoviral vectors (SAds) have been widely used to develop experimental genetic vaccines against several infectious diseases, including Ebola and RSV (Respiratory Syncytial Virus). These vectors have been administered in early and late stage clinical trials to several thousand individuals from different populations, including the elderly and neonates. Clinical and preclinical trials have shown that ReiThera's vaccine technology is safe and generates strong T cellular and antibody immune responses. ReiThera's new GRAd vector belongs to type C adenoviruses, which are considered to be among the most potent vectors to use as vaccines and at the same time have low seroprevalence in humans. This means that the immunogenicity of the GRAd vaccine is not hampered by pre-existing human anti-adenovirus antibodies.
Adenoviral vector vaccines can generate robust long-term immune system responses.
They underline this in an article published in the magazine Nature Immunology, scientists ofOxford University he was born in Cantonal Hospital St. Gallen, in Switzerland, who described the ability of adenovirus vaccines to generate robust and effective T cells. The team, led by Paul Klenerman of the University of Oxford, used an animal model to observe how vaccines of this type are able to enter fibroblastic reticular cells, which act as 'training grounds' for T cells
Authors show that adenovirus vectors can target specific cells, generating antigen deposits in these long-lived cells.. These biological units are very dynamic and can play an important role in immune control. "Adenoviruses have evolved together with humans for a long time - explained Burkhard Ludewig, professor at Cantonal Hospital St. Gallen - and have learned a lot about our immune system, so the T lymphocytes that come from these sources are very effective. ".
Scientists will continue to study pathways for immunization against emerging pathogens, in preclinical models and in clinical trials. "We hope to be able to use this new information in the design of new vaccines - concluded Ludewig - for example against diseases such as tuberculosis, HIV, hepatitis or cancer".