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Video: First Vector Vaccine For COVID-19 Shows Effect In Early Phase Of Human Study
First vector vaccine for COVID-19 shows effect in early phase of human study
This is the first complete data published in a scientific journal on a clinical trial of a Chinese vaccine against SARS-CoV-2. Earlier, the American company Moderna partially released data on the trial of its vaccine.
The first phase of a clinical study of the SARS-COV-2 coronavirus vector vaccine manufactured by CanSino Biologics has ended. The results are published in The Lancet. The vaccine showed a good safety profile, it was easily tolerated by volunteers, caused the appearance of specific T cells and the production of antibodies.
The CanSino vaccine trial began on the same day as the Moderna vaccine trial, March 16. Therefore, both of these vaccines can rightfully be called the first experimental vaccines against COVID-19, which began to be studied in humans. And this is the first complete data from a Phase I clinical trial of a SARS-COV-2 vaccine published in a peer-reviewed scientific journal.
Scientists criticized the publication on the intermediate successes of the first vaccine against COVID-19
Experts believe that the published data do not allow judging even the early criteria for the effectiveness of the vaccine.
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The vector vaccine was developed on the basis of an attenuated (non-pathogenic) adenovirus. A fragment (gene) of the SARS-CoV-2 virus is inserted into its genome. Adenoviruses must deliver the SARS-CoV-2 genes to the human body. To the proteins of the disease-causing virus, for the synthesis of which these genes are responsible, antibodies are produced in humans.
The Phase I study involved 108 people between the ages of 18 and 60. It showed that a single dose of a new vector vaccine based on adenovirus type 5 (Ad5-nCoV) triggers the production of specific antibodies and T cells after 14 days. Scientists rate its results as "promising as of 28 days after injection." The authors plan to conduct a final assessment of the level of antibodies in the blood of the participants in six months.
“These results need to be interpreted with caution. The ability to induce the production of antibodies does not mean that a vaccine will necessarily protect people from COVID-19,”said Professor Wei Chen of the Beijing Institute of Biotechnology.
Study participants were divided into three groups based on the dose of vaccine they received. Mild to moderate side effects were observed in 83% of people who received the low dose and 75% who received the high dose. They disappeared completely within 48 hours.
A Phase II clinical trial of this vaccine is starting in Wuhan. It involves 500 people: 250 will receive the vaccine at a medium dose, 125 at a low dose, and another 125 will receive a placebo group (control). This study, along with others, will include participants over the age of 60.
“Our study showed that if people were already immune to type 5 adenoviruses (Ad5), the production of immunity to SARS-CoV-2 could be slowed down and its peak level could be lower. Moreover, the existing immunity against Ad5 may negatively influence the duration of the vaccine-mediated immune response,”said Professor Feng-Cai Zhu of the Provincial Center for Control and Prevention, who led the study.
Whether this vaccine can truly protect people from COVID-19 should be shown by a Phase III study that tests the vaccine's prophylactic effect in real life.
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