The research team showed that the efficacy of SinoVac and BioNTech correlated with a unique bacterium, Bifidobacterium adolescentis. People who lacked Bifidobacterium adolescentis in their gut had a suboptimal antibody response in both vaccines.

The Centre for Gut Microbiota Research of the Faculty of Medicine at The Chinese University of Hong Kong (CU Medicine) is among the first in the world to discover that germs in our gut (gut microbiota) modulate our immunity and disease severity in novel virus. In a collaborative research project between CU Medicine and the LKS Faculty of Medicine at The University of Hong Kong (HKUMed), the research team showed that the efficacy of SinoVac and BioNTech correlated with a unique bacterium, Bifidobacterium adolescentis. They found that people who lacked Bifidobacterium adolescentis in their gut had a suboptimal antibody response to SinoVac. Among BioNTech recipients, those who lacked two types of bacteria including Bifidobacterium adolescentis also had lower antibody response. These novel findings imply that Bifidobacterium adolescentis can serve as a potential therapeutic option to enhance efficacy of SinoVac and BioNTech.

The results showed that over half of the people who received SinoVac had a suboptimal antibody response. There was a close correlation between low antibody response and the lack of a unique bacterium in our gut called Bifidobacterium adolescentis.

Among BioNTech recipients, those who lacked two bacteria including Bifidobacterium adolescentis also showed lower antibody response.

Those with the lowest antibody levels (lowest 25%) 

Bifidobacteria belong to a family of probiotic bacteria in our gut. Unlike other members of bifidobacteria, the team found that only Bifidobacterium adolescentis was associated with antibody response to SinoVac. Bifidobacterium adolescentis lives in our gut since birth and its abundance declines rapidly with age, modern diet, stress, and the use of antibiotics. Diet alone fails to restore this precious bacterium once it is lost.  Many health products contain Bifidobacteria but very few have Bifidobacterium adolescentis. In an earlier CUHK study of over 2,000 Hong Kong citizens, researchers found that Bifidobacterium adolescentis was either very low or absent in 85% of otherwise healthy Hong Kong people.   

“85% of the population are depleted in B. adolescentis in the gut”