The research team from the medical faculties of Chinese University and the University of Hong Kong collected blood and stool samples from 138 vaccinated people aged between 18 and 67, between April and August.
They found that 57 percent of the participants who received the Sinovac vaccine did not have enough antibodies against Covid.
They said they also found a close correlation between the presence of the Bifidobacterium adolescentis and a person’s antibody response to Covid vaccinations, saying participants lacking the bacteria tended to have a low antibody response.
Professor Ng Siew-Chien, associate director of Chinese University’s Centre for Gut Microbiota Research, said people cannot absorb the bacteria through their diet, but they could in future be given probiotics to boost the presence of the bacteria.
“I think this supplementation of Bifidobacterium adolescentis is going to really complement the global vaccination, regardless of whether it’s BioNTech or whether it’s Sinovac, because it can actually help to hopefully increase antibody level response in certain more susceptible population. So that in future, there may be a chance that this will be incorporated into the vaccination programme, because it’s healthy, it’s safe, and it doesn’t cause any side effect or harm,” she said.
“A lot of what is available in terms of probiotics may not have this bacteria, because you need special technology to capsulise the bacteria so that it can survive, so that when you consume it, it will actually reach your gut. So we encourage that when people are thinking about probiotics, do look very carefully whether the actual product has this type of bacteria and there are studies to support its use.”
In a previous study conducted by Chinese University, researchers found that around 50 percent of 2,000 participants in Hong Kong did not have Bifidobacterium adolescentis at all, while around 34 percent only had a low level of the bacteria.
Researchers said there are many factors that could reduce the number of the bacteria in a person’s gut, including old age and an unhealthy diet.
They said they are also carrying out a clinical study on some 500 people deemed to be more high-risk from Covid, including the elderly and people with diabetes and obesity, to find out more about the effectiveness of probiotics on improving their antibody response. They said they hope to release their findings early next year.
