Another study showing beneficial and protective effects of childhood diseases in early life - showing protection against asthma and allergies and atopies.

Jonathan I. Silverberg, Kevin B. Norowitz, Edward Kleiman, Helen G. Durkin, Tamar A. Smith-Norowitz. Varicella Zoster Virus (Wild-Type) Infection, but not varicella vaccine, in Late Childhood Is Associated With Delayed asthma Onset, Milder Symptoms, and Decreased Atopy. Pediatric asthma, allergy & Immunology: Volume 22, No. 1. 2009. Ahead of print. doi:10.1089/pai.2008.0515.

Varicella zoster virus (VZV) infection, early in life, has been shown to have a protective role against the development of asthma and atopy in children. It is unknown whether VZV infection in late childhood and adolescence also has an asthma protective effect. We studied whether VZV infection in late childhood and adolescence, or administration of the live attenuated varicella vaccine, provides a similar protective effect. In the present study, we use a retrospective chart review of a pediatric practice (N = 62) to analyze the effect of wild-type (WT) VZV infection or recombinant varicella vaccine in children (age 3-21 years) diagnosed with asthma. We found (1) asthma onset occurred 9.4 ± 4.4 years after WT VZV infection (4.4 ± 2.2) by age 13.9 ± 6.5 years, but only 3.0 ± 1.7 years after recombinant vaccine (3.2 ± 3.0 years) at age 5.0 ± 3.6 years (P = 0.05); (2) asthma classifications were 61.5% intermittent, 15.4% mild persistent, and 23.1% moderate persistent after WT VZV infection, but were 30.0% intermittent, 36.7% mild persistent, and 33.3% moderate persistent after recombinant vaccine (± = 0.01); (3) severe asthma flare-ups requiring inhaled or oral corticosteroids either d 1 year or > 1 year after infection occurred in 0.0% and 30.8% patients after WT infection, and 21.4% and 48.3% after recombinant vaccine (± = 0.01); and (4) history of allergies, necessity for allergy referral, and elevated serum IgE levels occurred in 15.4%, 7.7%, and 15.4% of patients who had WT VZV infection before asthma onset, and 36.7%, 33.3%, and 26.7% of patients who received recombinant vaccine (± = 0.01). These studies demonstrate that a single episode of varicella infection, even in late childhood and adolescence, is sufficient to delay the onset of asthma symptoms and decrease asthmatic symptoms and flare-ups.