This is the first complete clinical trial of a Chinese SARS-CoV-2 vaccine published in a scientific journal. Earlier, the American company Moderna partially published the data on the test of its vaccine.
The first phase of the clinical trial of the vector SARS-COV-2 coronavirus vaccine manufactured by CanSino Biologics has completed. Results published in the journal. Lancet. The vaccine showed a good safety profile, it was easily tolerated by volunteers, caused the appearance of specific T cells and antibody production.
The CanSino vaccine trial began on the same day as the Moderna vaccine trial, March 16th. 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 on a clinical trial of phase I vaccine against SARS-COV-2, published in a peer-reviewed scientific journal.
Vector vaccine is based on attenuated (pathogenicity-free) adenovirus. A fragment (gene) of the SARS-CoV-2 virus is embedded in its genome. Adenoviruses must deliver the SARS-CoV-2 genes to the human body. Antibodies to the proteins of the disease virus, the synthesis of which these genes are responsible for, are produced.
The Phase I study involved 108 people aged 18 to 60 years. It showed that a single dose of a new type 5 adenovirus vector vaccine (Ad5-nCoV) causes the production of specific antibodies and T cells after 14 days. Scientists evaluate its results as "promising as of 28 days after the introduction." The authors plan to conduct a final assessment of the level of antibodies in the blood of participants in six months.
“These results must be interpreted with caution. The ability to induce antibody production does not mean that the vaccine will protect people from COVID-19, ”said Professor Wei Chen of the Beijing Institute of Biotechnology.
Study participants were divided into three groups depending on the dose of vaccine they received. Mild or moderate side effects were observed in 83% of people who received a low dose, and in 75% who received a high. They completely disappeared within 48 hours.
A clinical trial of phase II of this vaccine begins in Wuhan. 500 people are participating in it: 250 will receive a vaccine in an average dosage, 125 in a low, and 125 more - a placebo group (control). This study, along with others, will include participants over 60 years of age.
“Our study showed that if people already had immunity to type 5 adenoviruses (Ad5), immunity to SARS-CoV-2 could slow down and its peak level could be lower. Moreover, existing anti-Ad5 immunity can adversely affect the duration of the vaccine-induced immune response, ”said Professor Feng-Cai Zhu of the Provincial Control and Prevention Center, which led the study.
Can this vaccine really protect people from COVID-19, a phase III study shows in which the preventive effect of the vaccine will be tested in real life.