China has several COVID-19 vaccine candidates underway, one of them based on the inactivated SARS-CoV-2 virus. Now, preliminary results of clinical trials confirm its safety and that iinduces immune response in healthy volunteers, also in those over 60 years old.

The experiments (in phase 1/2 of clinical trials) were carried out in China between April 29 and July 30 and had the participation of more than 600 volunteers healthy. The results of these tests are published in The Lancet Infectious Diseases.

Trials of this vaccine candidate (BBIBP-CorV) included participants between 18 and 80 years of age, and found that antibody responses were induced in all of them.

Participants aged 60 and older people took longer to respond; It took 42 days to detect the antibodies, compared with 28 days for participants aged 18 to 59.

The antibody levels were also lower in those aged 60 to 80 years compared to the other group (the mean neutralizing antibody titer 42 days after receiving the vaccine was 228.7 for persons aged 18 to 59 years and 170.9 for those aged 60 to 80 years).

The essays were not designed to assess efficacy of the vaccine, so it is not possible to say whether the antibody responses induced by the BBIBP-CorV vaccine are sufficient to protect against SARS-CoV-2 infection, the journal notes in its note.

Protect the elderly

Xiaoming Yang, one of the study’s authors, from the Beijing Institute of Biological Products, points out that protecting the elderly is a key goal for the success of the COVID-19 vaccine, as this group has a higher risk of suffering from a serious illness.

However, vaccines are sometimes less effective in them because the immune system weakens with age.

“So it is encouraging to see that BBIBP-CorV induces antibody responses in people 60 years of age or older, and we believe this warrants further investigation. “

Currently there 42 COVID-19 Vaccines in Clinical Trials and some have already been shown to be safe and elicit an immune response in the early stages of clinical trials, the journal recalls.

They vary depending on their typology and among them are the inactivated vaccines, like the one in this study, which is based on a sample of the virus that was isolated from a patient in China.

Booster shot

The virus stocks were cultured in the laboratory using cell lines and then they were inactivated using a chemical called beta-propionolactone.

According to trials, in which a number of participants were given placebo, the highest antibody responses were obtained with two doses of the vaccine on days 0 and 21 or 0 and 28.

For Yang, these findings indicate that a booster injection would be necessary to achieve the increased antibody responses against SARS-CoV-2 and could be important for protection. This provides useful information for a phase 3 trial.

The vaccine was safe and well tolerated at all doses tested, with no serious adverse reactions reported. The most common side effect was pain at the injection site.

The authors point out some study limitations, among them the short duration of follow-up, of only 42 days, and also that the study did not include children and adolescents under 18 years of age. Trials with these groups will be carried out when the analysis of the data with adults is complete.