COVID-19 Vaccine Induces Immune Response

BBIBP-CorV, an investigational COVID-19 vaccine, developed by the Beijing Institute of Biological Products and China National Pharmaceutical Group (Sinopharm), was found to be safe and induce an immune response in all participants in a phase 1/2 randomized controlled trial.

The findings were published today in The Lancet Infectious Diseases.

There were 2 phases of the study with the first looking at safety. Within this phase, there were 2 groups with one group having 96 participants aged between 18 to 59 years and 96 participants aged between 60 years and 80 years in the second group.

BBIBP-CorV was tested at 3 different dose levels (2mg, 4mg and 8mg,) with 2 vaccinations given 28 days apart. A fourth group within each age group (24 participants in each age group) were given 2 doses of a placebo vaccine. In total, in phase 1 of the study, 144 participants received the vaccine and 48 received the placebo.

Participants aged 60 and older took longer to respond--42 days before antibodies were detected in all recipients. In the younger cohort, the time to antibody detection in the whole group was 28 days.

Antibody levels were also lower in the older cohort. The mean neutralizing antibody titer 42 days after receiving a 8µg vaccine dose was 228.7 for the younger cohort, and 170.9 for the older group.

“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. However, vaccines are sometimes less effective in this group because the immune system weakens with age,” Professor Xiaoming Yang, one of the authors of the study, from the Beijing Institute of Biological Products Company Limited, said. “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.”

The second phase of the study was looking for the optimal timing schedule. 448 participants aged between 18 and 59 years were randomly assigned to receive either one 8mg shot of vaccine or placebo, or 2 shots of 4mg vaccine or placebo (at 14 days, 21 days. or 28 days apart).

In this second phase, there were 112 participants per group, with 336 receiving the vaccine, and 112 receiving the placebo.

The greatest antibody responses were elicited by 2 4mg doses 21 days or 28 days apart.

In terms of limitations, the investigators said there was a short duration of follow-up and no testing was done in adolescents and children. They are planning to test these participant groups after they fully analyze the adult studies.