An engineer demonstrates a plastic model of the Covid-19 coronavirus at the quality control laboratory at Sinovac Biotech’s Beijing facility.
Nicolas Asfuri AFP | Getty images
A potential coronavirus vaccine developed in China appears to provoke antibody neutralization in dozens of patients in an early-stage clinical trial, an important step in the development of a vaccine that can provide immunity to Covid-1
The vaccine candidate also induces binding antibodies in most patients within 28 days and appears to be safe and well tolerated, according to the results of a phase one trial published Friday in The Lancet.
“These results represent an important milestone,” said Wei Chen, a professor at the Beijing Institute of Biotechnology who led the study, in a press release. “However, these results must be interpreted with caution. The challenges in developing a vaccine against Covid-19 are unprecedented, and the ability to elicit these immune responses does not necessarily mean that the vaccine will protect people from Covid-19.”
The potential vaccine from CanSino Biologic, called Ad5-nCoV, was approved for human trials in March. Participants ranged in age from 18 to 60 years and received a low, medium, or high dose. There were 36 people in each of the three low, medium and high dose groups.
The concentration of neutralizing antibodies, which researchers say is important for gaining protection against the virus, appears to increase with dose strength, they said. By day 28, half of the patients in the low- and medium-dose groups showed neutralizing antibodies, compared with three-quarters of the patients in the high-dose group.
The researchers noted the small size of the sample and said further testing would be needed before the vaccine became available.
The results were published days after biotech company Moderna released early discoveries about its potential vaccine.
Moderna said her potential vaccine produces neutralizing antibodies for eight of the patients whose data are available so far. In addition, all 45 patients in the study produced binding antibodies seen at similar levels in people who had recovered from the virus, the company said.
There are no proven treatments for Covid-19. Scientists are optimistic that the vaccine to prevent the disease will be ready in the first half of 2021 – 12 to 18 months since Chinese scientists first identified the coronavirus and mapped its genetic sequence.
More than 100 vaccines are being developed worldwide, according to the World Health Organization. At least eight vaccines have been tested in humans.
The researchers hoped the antibodies would provide some degree of protection against Covid-19, but they can’t say for sure because it hasn’t been studied and some patients appear to have been re-infected after recovering from the virus.
In the CanSino Biologic vaccine study, most patients reported injection site pain, while others reported fever, fatigue, or headache, Chinese researchers said. One participant who received the higher dose reported severe fever along with severe symptoms of fatigue, shortness of breath and muscle pain. Reactions last less than 48 hours.
Researchers are now conducting a phase two trial with 500 patients.