A Chinese COVID-19 vaccine candidate based on the inactivated whole SARS-CoV-2 virus (BBIBP-CorV) is safe and elicits an antibody response The Lancet Infectious Diseases Found the magazine.
A previous clinical study reported similar results for another vaccine, also based on the inactivated whole SARS-CoV-2 virus. In this study, however, the vaccine was only tested in people under the age of 60.
The latest study enrolled participants between the ages of 18 and 80 and found that antibody responses were induced in all recipients. Participants aged 60 and over responded more slowly and took 42 days to detect antibodies in all recipients compared to 28 days for participants aged 18 to 59 years. Antibody levels were also lower in the 60-80 year olds compared to the 18-59 year olds (the mean neutralizing antibody titer 42 days after receiving an 8 μg dose of vaccine was 228.7 in the 18-59 year olds and 170, 9 for 60-80 year olds). .
The study was not designed to assess the effectiveness of the vaccine, so it cannot be said whether the antibody responses induced by the vaccine, called BBIBP-CorV, are sufficient to protect against SARS-CoV-2 infection.
Professor Xiaoming Yang, one of the authors of the study from the Beijing Institute of Biological Products Company Limited, Beijing, China said, “Protecting the elderly is a key goal of a successful COVID-19 vaccine as this age group is at greater risk of developing serious illness the disease. However, vaccines are sometimes less effective in this group because the immune system weakens with age. It is therefore encouraging to see that BBIBP-CorV induces antibody responses in people 60 years and older, and we believe this warrants further investigation. ”
There are currently 42 vaccines against COVID-19 in clinical trials. These vary in nature 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 in early clinical studies and trigger immune responses.
The BBIBP-CorV vaccine used in the study reported here is based on a sample of the virus isolated from a patient in China. Stocks of the virus were grown in the laboratory using cell lines and then inactivated using a chemical called beta-propionolactone. BBIBP-CorV contains the killed virus mixed with another component, aluminum hydroxide, called an adjuvant because it is known to increase the immune response.
In the first phase of the study, the optimal safe dose for BBIBP-CorV should be determined. 96 healthy volunteers between the ages of 18 and 59 and a second group of 96 participants between the ages of 60 and 80 were involved. Within each group, the vaccine was tested at three different doses (2 μg, 4 μg, and 8 μg, 24 participants per group) with two vaccinations given on days 0 and 28. A fourth group within each age group (24 participants in each age group) received two doses of a placebo vaccine. A total of 144 participants received the vaccine and 48 the placebo in phase 1 of the study.
The second phase of the study was designed to determine the optimal schedule for vaccination. 448 participants, aged 18 to 59 years, were randomly assigned to receive either an 8 g shot of vaccine or placebo or two shots of 4 μg vaccine or placebo (at 0 and 14 days, 0 and 21 days, or 0 and 28 days). In this second phase, there were 112 participants per group, of whom 336 received the vaccine and 112 received the placebo.
Participants were asked to report adverse events during the first seven days after each vaccination, which were reviewed by the research team. The participants then recorded adverse events with paper cards for the following 4 weeks. During phase 1, laboratory tests were carried out after the first and second vaccinations to assess kidney function, liver function and other organ functions. Blood samples were taken before and after vaccination to test the antibody levels for SARS-CoV-2.
No serious adverse events were reported within 28 days of the final vaccination. The most common side effect was pain at the injection site (Phase 1 results: 24%) [34/144] of vaccine recipients versus 6% [3/48] of placebo recipients). A small number of participants reported fever (Phase 1 results: 4%) [5/144] of vaccine recipients versus 6% [3/48] of placebo recipients). In none of the groups were clinically significant changes in organ functions found in laboratory tests.
The largest antibody responses were identified by two 4 µ G doses of vaccine triggered on either days 0 and 21 or 0 and 28 (mean neutralizing antibody titers 28 days after the second vaccination were 282.7 for two 4 µg injections on days 0 and 21 and 218.0 for two 4 µg injections on days 0 and 28).
Professor Xiaoming Yang said, “Our results show that a booster shot is necessary to get the largest antibody responses to SARS-CoV-2 and could be important for protection. This provides useful information for a phase 3 study. ”
The authors noted several limitations with the study, including the short follow-up period of only 42 days. They also stressed that the study did not include children and adolescents under the age of 18. Studies with these groups will be conducted when full analysis of the data from adult groups is complete, the researchers say.
Professor Larisa Rudenko from the Institute of Experimental Medicine in Saint Petersburg, Russia, wrote in a linked comment article: “[…] Further studies are needed to determine whether the inactivated SARS-CoV-2 vaccines are able to induce and maintain virus-specific T-cell responses, as the CD4-positive T-cells aid in optimal antibody responses as well important for cytotoxic CD8 is positive T-cell activation, which in turn is critical for virus clearance when the neutralizing antibody-mediated protection is incomplete. ”
The Chinese phase 2 study found the vaccine to be safe and to induce an immune response
Shengli Xia et al., Safety and Immunogenicity of an Inactivated SARS-CoV-2 Vaccine, BBIBP-CorV: A Randomized, Double-Blind, Placebo-Controlled Phase 1/2 Study, The Lancet Infectious Diseases (2020). DOI: 10.1016 / S1473-3099 (20) 30831-8
Quote: Preliminary results show the COVID-19 vaccine candidate based on the inactivated SARS-CoV-2 virus is safe (2020, October 16) and will be available on October 16, 2020 at https://medicalxpress.com/news/2020 -10-preliminary-results-covid was retrieved -vaccine-candidate.html
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