A COVID-19 vaccine developed in China has become the first involved in a Phase I clinical trial found to be safe, well-tolerated and able to generate an immune response by provoking neutralizing antibodies against the coronavirus that causes COVID-19, according to a new study published Friday in the prestigious medical journal, The Lancet. SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is the coronavirus that causes COVID-19.
The new vaccine is called "adenovirus type 5 vectored COVID-19 (Ad5-nCoV)" from CanSino Biologic, a Chinese vaccine company based in Tianjin. Ad5-nCoV is the first vaccine to be tested in humans. It's also the first COVID-19 vaccine candidate in the world to begin Phase II human trials after a successful Phase I trial.
Ad5-nCoV uses a weakened common cold virus (or an adenovirus) to deliver genetic material that codes for the SARS-CoV-2 spike protein to the cells. While capable of infecting human cells, the adenovirus used in Ad5-nCoV can't cause disease. These cells produce the spike protein characteristic of SARS-CoV-2. They travel to the lymph nodes where the immune system creates antibodies that recognize the spike protein and repel SARS-CoV-2.
The open-label trial involved 108 healthy adults. The study said the trial demonstrated promising results after 28 days. It pointed out the final results will be evaluated in six months. The study warned, however, new trials are needed to tell if the immune response it elicits effectively protects against SARS-CoV-2 infection.
Researchers also noted the small number of volunteers and said further research is needed before Ad5-nCo can become available. The Phase I trial was conducted in cooperation with the National Research Council of Canada (NRC).
"These results represent an important milestone," said Prof. Wei Chen from the Beijing Institute of Biotechnology. "The trial demonstrates that a single dose of the new adenovirus type 5 vectored COVID-19 (Ad5-nCoV) vaccine produces virus-specific antibodies and T cells in 14 days, making it a potential candidate for further investigation."
Prof. Wei, who was responsible for the study, said the results should be interpreted cautiously. He noted the challenges in the development of a COVID-19 vaccine are unprecedented.
He also warned the ability of Ad5-nCoV to trigger immune responses doesn't necessarily indicate the vaccine will protect humans from COVID-19. Prof. Wei said the results revealed in the study shows a promising vision for the development of COVID-19 vaccines, "but we are still a long way from this vaccine being available to all."
There are currently more than 100 candidate COVID-19 vaccines under development worldwide. Health experts agree an effective vaccine against COVID-19 is the long-term solution to controlling the global COVID-19 pandemic.
