NEW YORK (Reuters Health) Aug 13 - There is no association between varicella vaccine failure and asthma or inhaled steroid use in children, according to a report in the electronic pages of the August issue of Pediatrics. However, use of oral steroids does seem to be a risk factor.

"A sevenfold increased risk of breakthrough among vaccinated children with asthma was observed in a 1996 varicella outbreak in a child care center," note Dr. Robert T. Chen with the National Immunization Program at the Centers for Disease Control and Prevention in Atlanta, Georgia, and colleagues.

To investigate further, the team examined data on varicella occurring more than 42 days after vaccination among children born after 1993 and followed through 1999 at two health maintenance organizations (HMOs A and B).

Among 80,584 children vaccinated against varicella at HMO A and 8181 vaccinated at HMO B, the investigators observed 268 and 97 breakthrough cases, respectively. There was no association between varicella breakthrough and asthma, inhaled steroids prescribed at any time, or oral steroids prescribed before varicella vaccination.

The risk of varicella breakthrough was increased in the 3 months immediately after prescription for oral steroids at HMO A (adjusted relative risk = 2.4) and HMO B (adjusted RR = 2.8).

"The previous finding of asthma as a risk factor for vaccine failure may be attributable to the confounding effect of [oral] steroid treatment for asthma, which was not examined," the investigators conclude.

Pediatrics 2003;112:e98-e103.