Taking antibiotics in the first two years of life can prevent babies from developing a strong immune response to certain vaccines. The new finding provides another cautionary tale against antibiotic overuse, the researchers say.
Babies are vaccinated in their first six months and receive booster shots in their second year to protect against certain infectious diseases. Antibiotic use during that time was associated with poor immune responses to four vaccines that babies receive to prevent whooping cough, polio and other diseases, researchers report online April 27 at Pediatrics.
And the more rounds of antibiotics a child received, the more levels of vaccine antibodies fell below what is considered protective. Levels induced by the primary series of vaccines for poliomyelitis, diphtheria-tetanus-pertussis, Haemophilus influenzae pneumococcal b-type vaccines fell 5 percent to 11 percent with each course of antibiotics. In the children’s second year, antibody levels generated by booster shots of these vaccines were reduced by 12 percent to 21 percent per cycle.
“If anyone needed yet another reason why antibiotic overprescription is not a good thing, this article provides that reason,” says immunologist Bali Pulendran of the Stanford University School of Medicine, who was not involved in the study.
Taking antibiotics disrupts the population of bacteria that live in the intestine. That’s well known, but researchers are still learning how that disruption can affect a person’s health. The new study adds to evidence that decreasing the number and diversity of gut bacteria affects vaccination. In studies in mice, antibiotics hampered the immune system’s response to vaccines. And a small human study found that antibiotics blunted the response of adults to the flu vaccine in those whose previous immunological memory for influenza had decreased, Pulendran and his colleagues reported in 2019.
the study in Pediatrics is the first to report an association between antibiotic use and compromised vaccine responses in children. Michael Pichichero, a pediatric infectious disease specialist at the Rochester General Hospital Research Institute in New York, and his colleagues collected blood samples from 560 children during routine visits with their pediatricians. Of these, 342 children had been prescribed nearly 1,700 courses of antibiotics and 218 children had not received the drugs. The team analyzed whether the levels of antibodies induced by the four vaccines reached the threshold considered protective and found that the levels were lower for children who had received antibiotics.
The type and duration of antibiotic treatment also made a difference. Broad-spectrum drugs were associated with antibody levels below what is protective, while a more specific antibiotic was not. In addition, a 10-day course, but not a five-day course, reduced vaccine-induced antibody levels.
The researchers did not look at whether children in the study with reduced antibody levels were more likely to develop vaccine-preventable diseases. But there has been concern about whooping cough outbreaks, says Pichichero, that have occurred in the United States despite vaccination (Serial number: 4/4/14). Perhaps the use of antibiotics can help explain these outbreaks, he says.
To see what kinds of changes are occurring in the gut bacteria, Pichichero and his colleagues are starting a study with a new group of children. Investigators will collect stool samples along with blood draws and records of antibiotic use. They would like to follow the children after age 5, beyond the time the children receive another round of booster shots, to see if antibiotics also interfere with this next opportunity to develop antibodies.
“Antibiotics are miracle medicines,” says Pichichero. “In no way does this study imply that children who need an antibiotic should not receive it.” But if possible, it should be a narrow-target antibiotic for a shorter course, he says. Along with the risk of antibiotic resistance that comes with overuse of the drugs (Serial number: 01/24/22), the impact that antibiotics could have on vaccine-induced immunity “has clinical implications for each individual child.”