The first COVID-19 vaccine to reach a phase 1 clinical trial has been found to be safe, well-tolerated and capable of generating an immune response in humans against SARS-CoV-2, the novel coronavirus that has caused the global pandemic, according to research published in the medical journal The Lancet on May 22.

The open-label trial in 108 healthy adults demonstrated promising results after 28 days — the final results will be evaluated in six months.

Further trials are needed to determine whether the immune response the vaccine elicits effectively protects against SARS-CoV-2 infection, according to researchers.

"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 Chen Wei, from the Beijing Institute of Biotechnology in Beijing, who is responsible for the study.

"However, 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," Chen said.

The creation of an effective vaccine is seen as a long-term solution to controlling the COVID-19 pandemic. Currently, there are more than 100 COVID-19 vaccine candidates in development worldwide.

Volunteers involved in the trial were from Wuhan, capital of Hubei province. They were between 18 and 60 years old and did not have the SARS-CoV-2 infection.