Preliminary results have found that COVID-19 vaccine candidates based on the inactivated SARS-CoV-2 virus are safe.

China’s COVID-19 vaccine candidate, which is based on the inactivated whole SARS-CoV-2 virus (BBIBP-CorV), is safe and elicits an antibody response. This is the result of a small early-stage randomized clinical trial published today. Lancet infection The journal was found.

Previous clinical trials reported similar results for another vaccine based on the inactivated whole SARS-CoV-2 virus, but in that study the vaccine was tested only in people under the age of 60. It was.

The latest study included participants between the ages of 18 and 80 and found that all recipients elicited an antibody response. Participants over the age of 60 were slow to respond and took 42 days ago antibody Detected in all recipients compared to 28 days for participants aged 18-59 years. Antibody levels were also lower in 60-80 years than in 18-59 years (mean neutralizing antibody titers 42 days after 8 μg vaccine administration were 228.7 in 18-59 years and 170.9 in 60-80 years. was) .

This study was not designed to evaluate the efficacy of the vaccine, so it was determined whether an antibody response induced by a vaccine called BBIBP-CorV was sufficient to protect against SARS-CoV-2 infection. Cannot be done.

Professor Xiaoming Yang, one of the authors of the Beijing Institute of Biological Products Company Limited in Beijing, China, said: “As this age group grows, protecting the elderly is an important goal of the success of the COVID-19 vaccine. However, in this group, the immune system weakens with age, making the vaccine less effective. Therefore, it is encouraging to confirm that BBIBP-CorV induces an antibody response in people over the age of 60, and I believe this. Justify further investigation. “

Currently, there are 42 COVID-19 vaccines in clinical trials. These vary in type and include DNA plasmid vaccines, inactivated virus vaccines, adenovirus vector vaccines, RNA vaccines, protein subunit vaccines, and virus-like particle vaccines.Some of these have already been shown to be safe and elicit an immune response in the early stages. Clinical trial..

The BBIBP-CorV vaccine used in the studies reported here is based on a sample of virus isolated from a Chinese patient.Virus stock in the lab Cell line It is then inactivated using a chemical called beta proprionolactone. BBIBP-CorV contains the killed virus mixed with another component, aluminum hydroxide. Aluminum hydroxide is called an adjuvant because it is known to stimulate the immune response.

The first phase of the study was designed to find the optimal safe dose of BBIBP-CorV. A second group of 96 healthy volunteers between the ages of 18 and 59 and 96 participants between the ages of 60 and 80 participated. Within each group, the vaccine was tested at three different dose levels (2 μg, 4 μg and 8 μg, 24 participants per group), with two vaccinations on days 0 and 28. The fourth group within each age group (24 participants in each age group) was vaccinated twice with the placebo vaccine. In total, in Phase 1 of the study, 144 participants received the vaccine and 48 received the placebo.

The second phase of the study was designed to identify the optimal timing schedule for vaccination. 448 participants aged 18-59 years receive one 8 μg shot of vaccine or placebo or two shots of 4 μg vaccine or placebo (0-14 days, 0-21 days, or 0-28 days) Was randomly assigned. In this second phase, there were 112 participants in each group, 336 received the vaccine and 112 received the placebo.

Participants were asked to report adverse events during the first 7 days after each vaccination, which were validated by the research team. Participants then used paper cards to record adverse events for the next four weeks.In Phase 1, clinical tests were performed and evaluated after the first and second vaccinations. Renal function, Liver function and other organ functions. Blood samples were taken to test SARS-CoV-2 antibody levels before and after vaccination.

No serious adverse events were reported within 28 days of the last vaccination. The most common side effect was pain at the injection site (Phase 1 results: 24%) [34/144] 6% of vaccinated people [3/48] Of a placebo recipient). A small number of participants reported experiencing fever (Phase 1 results: 4%) [5/144] 6% of vaccinated people [3/48] Of a placebo recipient).There were no clinically significant changes in organ function detected in Laboratory test In one of the groups.

Maximum antibody response was elicited by two 4 μg doses of vaccine on either day 0 and 21 or days 0 and 28 (mean neutralization 28 days after the second vaccination). The antibody titer was 282.7 for two 4 μg injections on days 0 and 21, and 218.0 for two 4 μg injections (day 0 and 28 injections).

“Our findings show that booster shots are needed to achieve maximum antibody response to SARS-CoV-2 and may be important for defense,” said Professor Xiaoming Yang. This provides useful information for Phase 3 trials. “

The authors noted that the study had some limitations, including a short follow-up period of only 42 days. They also emphasized that the study did not include children and adolescents under the age of 18. Studies in these groups will take place when a complete analysis of the data from the adult group is complete, the researchers say.

Professor Larisa Rudenko, who was not involved in the study at the Institute of Experimental Medicine in St. Petersburg, Russia, wrote in a linked commentary:[…] More research is being done to establish whether the inactivated SARS-CoV-2 vaccine can induce and maintain a virus-specific T cell response, as the help of CD4-positive T cells is important for optimization. Is required. Antibody reactionIt is important for the activation of cytotoxic CD8-positive T cells, and for viral clearance in the event of incomplete protection via neutralizing antibodies. ”