Covid-19 vaccine tested in Wuhan induces rapid immune response

A researcher works on a Covid-19 vaccine. PHOTO | FILE | AFP

A Covid-19 vaccine studied in Wuhan, China, has been found safe and induces rapid immune response.

The findings were published on Friday, days after an American biotechnology company announced that it had also developed a vaccine that has been found to be safe and able to stimulate an immune response in the human body against the virus.

Data on the vaccine developed by a Chinese drug maker, CanSino Biologics, were published in the Lancet, making it the first Covid-19 vaccine candidate, whose phase one trial data have been published in a scientific journal. This happens to be the second vaccine to show success in a week, although the first one by Moderna, an American biotech, has been contested after the firm failed to share data from its phase one trials.


The study on 108 adults found that one dose of the vaccine, known as recombinant adenovirus type-5 vectored Covid-19 vaccine (AD5), tested at three different levels on healthy adults aged between 18 and 60 years, appeared to induce a good immune response in some subjects.

The researchers tested the blood of volunteers (enrolled from one site in Wuhan) at regular intervals following vaccination to see whether the vaccine stimulated both arms of the immune system: the body’s ‘humoral response — the part of the immune system that produces neutralising antibodies, which can fight infection and could offer a level of immunity — and the body’s cell-mediated arm, which depends on a group of T cells, rather than antibodies, to fight the virus.

The ideal vaccine might generate both antibody and T cell responses to defend against Sars-CoV-2.

“These results represent an important milestone. 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,” said Prof Wei Chen from the Beijing Institute of Biotechnology, who is responsible for the study.

The vaccine uses a live but weakened common cold virus called adenovirus 5 onto which genetic material of the Sars-CoV-2 virus is fused. The Ad5 virus then acts as an effective delivery system that teaches the immune system to recognise the coronavirus.


The Ad5 virus infects human cells readily but is incapable of causing disease.
The vaccine evaluated in this trial is the first to be tested in humans. But many people have had previous infections with adenovirus 5, raising concerns that the immune system would focus on the Ad5 parts of the vaccine rather than the Sars-Cov-2 part, notes STAT Magazine.

Although the vaccine that was given as an intramuscular injection produced neutralising antibodies and T-cell responses against the Sars-CoV-2 virus, further research is needed to confirm whether the vaccine protects against infection.

For this, Prof Chen put a caveat to the findings saying: “These results should be interpreted cautiously. The challenges in the development of a Covid-19 vaccine are unprecedented, and the ability to trigger these immune responses does not necessarily indicate that the vaccine will protect humans from Covid-19. This result 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.”

With countries slowly reopening their economies by lifting lockdowns, the creation of an effective vaccine is seen as the long-term solution to controlling the Covid-19 pandemic. Currently, there are more than 100 candidate vaccines in development worldwide. The final results of the study will be evaluated in six months.