A new study from a team of Australian researchers suggests antibiotic use in babies can impair the efficacy of several key vaccinations administered in the early years of life. The study hypothesizes that antibiotics can disrupt an infant's developing gut microbiome, which can subsequently reduce the effectiveness of a vaccination.

"It appears that antibiotics in the first year of life change the way the body builds immunity – and responds to vaccination," says David Lynn, lead on the research team from Australia's Flinders University.

At this stage, the research has only been confirmed in animal models, but it found that mice exposed to antibiotics displayed reduced immune responses to five vaccines routinely administered to infants. The vaccines studied included ones for meningitis, pneumonia, tuberculosis and whooping cough.

It is hypothesized that the antibiotics' disruptive effect on an infant's growing microbiome was the reason behind the reduced immune response to the vaccines. To confirm this connection the researchers performed a fecal microbiota transfer between untreated mice and mice exposed to antibiotics. Once a bacterial diversity was returned to the microbiome of the antibiotic-treated mice, a corresponding improvement in immune response to the vaccines was identified.

The study interestingly found that adult mice exposed to similar levels of antibiotics did not demonstrate the same impaired immune response to vaccines as infant mice. This suggests that the damage done by antibiotics in infants is more significant than in adults.

More research still needs to be done following this early study, firstly to verify these results in human subjects. A clinical study engaging infants is currently underway at the Women's and Children's Hospital in Adelaide to understand how transferable these results are to people.

It's hoped that further research will reveal exactly how the microbiome can regulate the efficacy of vaccines and whether supplements can be administered to infants following antibiotic exposure. Restoring and repairing a disrupted microbiome in infants through either diet or probiotics could be an exciting and simple way to enhance the overall efficacy of vaccine responses.

The research was published in the journal Cell Host & Microbe.