Chinese COVID-19 vaccine candidate shows promise in human trial, study finds

A leading candidate for China’s COVID-19 vaccine, called BBIBP-CorV, was shown to be safe and elicited an immune response in a small early-phase human trial, researchers said Friday. A previous clinical trial reported similar results for a different vaccine that is also based on the inactivated whole SARS-CoV-2 virus, but in that study the vaccine was only tested in people younger than 60 years.

The latest study, published in The Lancet Infectious Diseases, included participants between the ages of 18 and 80 and found that antibody responses were induced in all receptors. It took 42 days for participants 60 and older to detect antibodies in all recipients, compared with 28 days for participants 18 to 59 years old, the researchers said.

Antibody levels were also lower in those 60 to 80 years old compared to those 18 to 59 years old, they said. The BBIBP-CorV vaccine used in the study is based on a sample of the virus that was isolated from a patient in China. Stocks of the virus were grown in the laboratory using cell lines and then inactivated with a chemical called beta-propionolactone.

BBIBP-CorV includes the killed virus mixed with another component, aluminum hydroxide, which is called an adjuvant because it is known to stimulate immune responses. The trial was not designed to evaluate the efficacy of the vaccine, so it is not possible to say whether the antibody responses induced by the vaccine, called BBIBP-CorV, are sufficient to protect against SARS-CoV-2 infection, according to researchers.

“Protection of the elderly is a key goal of a successful COVID-19 vaccine, as this age group is at increased risk of severe illness due to the disease,” said Professor Xiaoming Yang, one of the study authors , from the Beijing Institute of Biology. Products Company Limited.

“However, vaccines are sometimes less effective in this group because the immune system weakens with age. Therefore, it is encouraging to see that BBIBP-CorV induces antibody responses in people 60 years of age and older, and we think this warrants further investigation, ”Yang said.

There are currently 42 vaccines for COVID-19 in clinical trials, the researchers noted. These vary in type and include plasmid DNA vaccines, inactivated virus vaccines, adenovirus vectored vaccines, RNA vaccines, protein subunit vaccines and virus-like particle vaccines, they said.

Some of these have already been shown to be safe and elicit immune responses in early-phase clinical trials. The first phase of the study involved 96 healthy volunteers between the ages of 18 and 59 and a second group of 96 participants between the ages of 60 and 80.

Within each group, the vaccine was tested at three different dose levels, with two vaccines administered on days 0 and 28. A fourth group within each age group received two doses of a placebo vaccine.

In the second phase of the study, 448 participants ages 18 to 59 were randomized to receive one 8-microgram injection of vaccine or placebo, or two injections of 4-microgram vaccine or placebo. No serious adverse events were reported within 28 days of the final vaccination, and the most common side effect was pain at the injection site, the researchers said. There were no cases of clinically significant changes in organ functions detected in laboratory tests in either group, they said.

The highest antibody responses were elicited by two 4-microgram doses of the vaccine on days 0 and 21 or 0 and 28, according to the researchers. “Our findings indicate that a booster vaccine is necessary to achieve the highest antibody responses against SARS-CoV-2 and could be important for protection. This provides useful information for a phase 3 trial, ”Yang said.

The researchers noted some limitations with the study, including the short duration of follow-up of just 42 days. They also noted that the study did not include children and adolescents under 18 years of age.

“More studies are needed to establish whether inactivated SARS-CoV-2 vaccines are capable of inducing and maintaining virus-specific T-cell responses,” said Professor Larisa Rudenko of the Russian Institute of Experimental Medicine, who was not involved in the study. This is because the help of CD4 positive T cells is important for obtaining optimal antibody responses, as well as for the activation of cytotoxic CD8 positive T cells, which, in turn, are crucial for viral shedding if protection mediated by neutralizing antibodies is incomplete, Rudenko said.