Preliminary research shows a COVID-19 vaccine that uses an inactivated version of the coronavirus is safe and can elicit an antibody response.
Published in the journal Lancet Infectious Disease, researchers from China shared their findings from small early-phase randomized clinical trials involving 466 participants between ages 18 and 80. So far, an antibody response was found in all age groups of participants.
The vaccine, known as BBIBP-CorV, was given on a two-dose schedule. The first phase was designed to find the optimal safe dose, testing three different dose levels (2 μg, 4, μg, and 8 μg). In total, 144 participants received the vaccine and 48 received the placebo in the first phase.
In the second phase, researchers studied the optimal time for vaccination. In total, 448 participants between the ages of 18 and 59 were randomly assigned to receive either one 8μg shot of vaccine or placebo, or two shots of 4μg vaccine or placebo (at 0 and 14 days, 0 and 21 days or 0 and 28 days).
Researchers took blood samples from participants on days 7, 14, 28, 32, and 42 after vaccination. In the most vulnerable group — volunteers aged 60 and older — antibodies took up to 42 days to be detected in blood tests, while it took 28 days for those 18 to 59.
This is the first study that uses the inactivated SARS-CoV-2 virus in people older than 60 years. The older age group saw lower rates of adverse events than the younger adults. Within 28 days after vaccination, 34 out of 72 participants (47 per cent) participants aged 18 to 59 years had an adverse reaction, compared with 14 of 72 (19 per cent) of participants aged 60 years and older. The most common side-effect was pain at the site of injection, but no serious adverse events were reported. Fever was reported in five of 144 (four percent) of vaccine recipients.
“Protecting older people is a key aim of a successful COVID-19 vaccine as this age group is at greater risk of severe illness from the disease,” says study author Xiaoming Yang, from the Beijing Institute of Biological Products Company Limited, which is developing the BBIBP-CorV vaccine in affiliation with Sinopharm, a Chinese pharmaceutical company.
He also noted that 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 aged 60 and older, and we believe this justifies further investigation,” he said. “Our findings indicate that a booster shot is necessary to achieve the greatest antibody responses against SARS-CoV-2 and could be important for protection. This provides useful information for a phase 3 trial.”
While the vaccine so far seems to be tolerable and able to generate an immune response in healthy people, further study is needed. None of the participants in this study had underlying diseases, which is a major risk factor. According to the WHO, 96 per cent of all those who have reportedly died from COVID-19 had at least one underlying condition, with cardiovascular disease being the leading comorbidity.
There are currently 44 vaccines for COVID-19 in clinical trials.