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Broad and learned
clinical background

Gut Reactions #4 – H pylori: a new oral vaccine?

Helicobacter pylori (H pylori) is a very common bacterial infection of the stomach lining, affecting at least half the world’s population. It is thought to be caught in childhood. In some people H pylori may increase the amount of acid produced by the stomach and lead to duodenal ulceration. The majority of people with H pylori infection will be unaware of the infection or may develop intermittent indigestion (dyspepsia). There is the further association between long-standing infection with H pylori and an increase in the risk of developing stomach cancer.

In June this year, researchers from China published results of a trial to determine the effectiveness and safety of a new oral vaccine against H pylori. The findings of this trial are of importance because until now, several other H pylori vaccine candidates have all proven to be ineffective in humans.

The trial consisted of giving the vaccine to nearly 4,500 healthy children (without past or present H pylori infection). Interestingly, the vaccine was effective at preventing infection in about 72% of children at 1 year, 55.0% in year 2, and 56% in year 3 after vaccination. Although these findings show that the vaccine reduced risk of H pylori infection for up to 3 years, we are still lacking evidence regarding its potential for long term protection. This is important to consider because most of the diseases associated with the bacterium occur in adults and therefore many decades after catching the infection.

We hope that these findings will renew medical interest in oral vaccines for H pylori, and will stimulate further development, research and clinical trials.