Children who delayed the timing of the DPT vaccine had lower rates of asthma.
Delay in diphtheria, pertussis, tetanus vaccination is associated with a reduced risk of childhood asthma?
McDonald KL, Huq SI. Journal of the American Academy of Allergy, Asthma and Immunology. 2008;121:626-631.
“Early childhood immunizations have been viewed as promoters of asthma development by stimulating a T(H)2-type immune response or decreasing microbial pressure, which shifts the balance between T(H)1 and T(H)2 immunity. Among 11, 531 children who received at least 4 doses of DPT, the risk of asthma was reduced to (1/2) in children whose first dose of DPT was delayed by more than 2 months.”