China has begun the second phase of clinical trials for a COVID-19 vaccine with 500 volunteer participants recruited from Wuhan, the initial epicenter of the outbreak, according to state media.
It is the first Phase 2 human test for a COVID-19 vaccine in the global race to find a cure for the pandemic, the official Xinhua News Agency said Tuesday.
China completed its Phase 1 trial at the end of March with 108 volunteers. All of them reportedly have been released from medical observation and are in good health.
While the first phase focused on the vaccine’s safety, the second phase inoculates many more people to determine how effective it is in protecting against infection. The trial reportedly started last Sunday by a research team led by Chen Wei, a virologist in China's military.
Video released by China's state broadcaster CCTV Wednesday showed an 84-year-old man in Wuhan receiving a vaccination Monday, becoming the oldest volunteer in the Phase 2 trial.
Unlike the Phase 1 trial, which had a maximum age of 60, Phase 2 has no age limit. Because elderly patients have the highest death rates, this trial is trying to determine what the antibody response is in the elderly compared with the young. Phase 2 trials also typically determine how many doses are necessary to create immunity and create a profile of common reactions.
A race, but not rushed
Chen's team and U.S.-based biotechnology company Moderna Therapeutics appeared to launch Phase 1 clinical trials on the same day last month. With Tuesday’s announcement, China appears to have become the first to enter the Phase 2 trial.
In China, the global race for a vaccine is routinely framed as a competition on state media. A headline by Xinhua proudly reads China "is the first to enter Phase 2 clinical trials." A video released on the CCTV website last week was titled "China vs. U.S. — Whose Vaccine With More Hope?"
Wu Zunyou, chief expert in epidemiology at the Chinese Center for Disease Control and Prevention, said last month that it might take China just six months to determine if its vaccine is effective and safe.
On the other hand, public health officials around the world have been warning that a COVID-19 vaccine cannot be rushed. They said a safe and effective vaccine may not be available to the public for at least 12 to 18 months.
There have been tragic results in the past from flawed vaccine development, and some researchers have urged teams to use animal models, as well as extensive human clinical trials, to ensure the COVID-19 vaccine does not cause unintended side effects.
The U.S. Centers for Disease Control and Prevention estimates that Phase 2 trials will last several months to two years, and Phase 3 trials can last several years.
If Phases 1 and 2 are considered successful, China will proceed to Phase 3, which involves administering the vaccine to thousands of people. As China reports fewer coronavirus infections, medical authorities have indicated the experimental vaccine may be tested abroad.
