The study has several limitations. The antibiotic prescription data and measurements of vaccine-induced antibody levels were recorded and measured prospectively; however, our analysis was done retrospectively. The group of study children was derived from my private practice in Rochester, N.Y., and may not be broadly representative of all children. The number of vaccine antibody measurements was limited by serum availability at some sampling time points in some children; and sometimes, the serum samples were collected far apart, which weakened our ability to perform longitudinal analyses. We did not collect stool samples from the children so we could not directly study the effect of antibiotic courses on the gut microbiome.
Our study adds new reasons to be cautious about overprescribing antibiotics on an individual child basis because an adverse effect extends to reduction in vaccine responses. This should be explained to parents requesting unnecessary antibiotics for colds and coughs. When antibiotics are necessary, the judicious choice of a narrow-spectrum antibiotic or a shorter duration of a broader spectrum antibiotic may reduce adverse effects on vaccine-induced immunity.
References
1. Valdez Y et al. Influence of the microbiota on vaccine effectiveness. Trends Immunol. 2014;35(11):526-37.
2. Lynn MA et al. Early-life antibiotic-driven dysbiosis leads to dysregulated vaccine immune responses in mice. Cell Host Microbe. 2018;23(5):653-60.e5.
3. Hagan T et al. Antibiotics-driven gut microbiome perturbation alters immunity to vaccines in humans. Cell. 2019;178(6):1313-28.e13.
4. Chapman T et al. Antibiotic use and vaccine antibody levels. Pediatrics. 2022;149(5);1-17. doi: 10.1542/peds.2021-052061.