The Truth About Vaccines, page-2953

http://news.flinders.edu.au/blog/2018/05/10/can-antibiotics-impair-babys-vaccine-response/

"Antibiotic exposure in infants could impair their responses to five important routine vaccines administered daily around the world, new research has found.
Flinders University Associate Professor Lynn says that results of preclinical modelling, and more research in clinical trials, could change the way children are given antibiotics and have significant implications for vaccination programs.
“The research findings are very important because by one year of age, 50 per cent of infants in Australia will be exposed to antibiotics, and this is the period of life that many of these vaccines are administered,” he says.
“It appears that antibiotics in the first year of life change the way the body builds immunity – and responds to vaccination,” says Associate Professor Lynn, who leads the European Molecular Biology Laboratory (EMBL) Australia biomedical informatics group at the Infection and Immunity theme at the South Australian Health and Medical Research Institute (SAHMRI) in Adelaide.
“We have showed that the bacteria in the gut (the microbiome) are important in shaping the strength of the infant immune system,” Associate Professor Lynn says.
“Our findings could have significant implications for vaccination programs globally.”"

Rest of article in link above.