WUHAN, China — The first experimental coronavirus vaccine demonstrates potential in controlling the COVID-19 pandemic. Researchers at China’s CanSino Biologics Inc., reported on a Friday in The Lancet medicinal journal that CanSino’s coronavirus vaccine, recombinant adenovirus type 5 (Ad5) vectored COVID-19 vaccine, is safe, tolerable and produces an immune response at 28 days post-vaccination.
The primary endpoint for safety was the occurrence of adverse reactions within 7 days after the vaccination. The onset of detectable immune responses were rapid, with T-cell responses peaking at day 14 and specific humoral responses against SARS-CoV-2 peaking at day 28 post-vaccination.
“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”
Prof. wei chen from beijing institute of technology
Data has only shown results 28 days after the vaccination. According to the researchers, a follow up on the vaccine recipients will be conducted after six months in order to obtain more data.
Further studies will be needed to confirm whether the vaccine will provide immunity against the virus.
“However … the ability to trigger these immune responses does not necessarily indicate that the vaccine will protect humans from COVID-19 … we are still a long way from this vaccine being available to all.”
PROF. WEI CHEN FROM BEIJING INSTITUTE OF TECHNOLOGY
There are several candidate vaccines in development worldwide. Among them are Moderna’s mRNA COVID-19 vaccine and CanSino’s non-replication adenovirus type 5 (Ad5) vectored COVID-19 vaccine which both entered phase 1 clinical trials on March 16, 2020.
The Ad5 vectored COVID-19 vaccine was developed by Beijing Institute of Biotechnology and CanSino Biologics. The vaccine is a replication defective Ad5 vectored vaccine expressing the S-glycoprotein which facilitates the entry of SARS-CoV-2 into the host cell.
Phase 1
Researchers of CanSino conducted the research in Wuhan, Hubei province, China. The study included 108 adults aged between 18-60 years who tested negative for SARS-CoV-2 infection. The participants were further divided into 3 dose groups: a low-dose group, a middle-dose group and a high-dose group.
A single shot was administered intramuscularly in the arm of the participants. Those in the low-dose group received a shot with one vial. The participants included in the middle-dose group each received a shot with two vials. Participants in the high-dose group received a double-shot regimen with one vial on one arm and two vials in the other arm.
Investigators verified adverse events that were self-reported by the participants during the first 14 days post-vaccination. The most commonly reported systemic adverse reactions overall were fever, fatigue, headache and muscle pain. Most adverse reactions reported were mild or moderate in severity.
Across all dose groups, high proportions of participants with positive T-cell responses were observed post-vaccination. The activation of specific humoral responses against SARS-CoV-2, such as CD4+ cells and CD8+ cells were also evident in the vaccine recipients.
Phase 2 trial (NCT04341389) is already underway in Wuhan, China.