In vaccinated with whole-cell vaccine, the risk of allergy was 76% higher. In those who took antibiotics in the first two years of life, the risk of allergy was 2 times higher.
Taking one course of antibiotics increased the risk of developing an allergy by 85%, two courses of antibiotics increased the risk 3-fold, and three courses of antibiotics increased the risk 8-fold.
Those who had measles and had not received the vaccine, had a 45% lower risk of developing an allergy (note: in this case there was no statistical significance).
A systematic review of the effect of antibiotics on whooping cough conducted by Cochrane found that while antibiotics kill pertussis and reduce the probability that a person transmits the disease, they do not affect the actual course of the disease.
The use of antibiotics to help prevent infants from contracting pertussis is ineffective. Research has demonstrated that the use of antibiotics among children only leads to a longer illness.
The use of antibiotics subsequently increases the risk of pneumococcal infection, as well as the risk of Hib, meningitis, infections with Staphylococcus aureus, Salmonella and Campylobacter, typhoid fever, boils, mastitis, acute respiratory infections, and urinary tract infections.Seven-Valentine Pneumococcal Conjugate Vaccine and Nasopharyngeal Microbiota in Healthy Children. 2014, Biesbroek, Emerg Infect Dis
In those who got pneumococcal vaccines, there are fewer pneumococcal bacteria of non-vaccine serotypes in the upper respiratory tract, but more H. influenzae and staphylococcus, as well as much more anaerobic bacteria. Some of these bacteria are known to increase the risk of otitis media. Temporary bacterial imbalance also increases the risk of otitis media.
Those taking antibiotics had 4 times fewer corynebacteria and Dolosigranulum, but 6.3 times more staphylococcus.