Introduction Varicella zoster virus (VZV) infection can result in significant morbidity in patients with cystic fibrosis (CF), and the risk of severe pulmonary complications rises with age. This is a greater concern in those immunosuppressed due to systemic corticosteroid treatment for allergic bronchopulmonary aspergillosis (ABPA). Severe complications such as pneumonitis, secondary bacterial infections, and liver failure may occur despite prompt treatment with antiviral agents. The seroprevalence of VZV antibodies in CF children is unknown, although in the general population >80% children over 6 years of age have evidence of immunity.1 We aimed to investigate the seroprevalence of VZV antibodies in children attending a large paediatric specialist CF centre, even if there was a history of chicken pox.
Methods In 2011 we started routine testing for VZV antibodies in 6 year olds at their annual review. This age was selected in view of the low prevalence of ABPA under that age (2/90 in our clinic), and the chance that children would already have had chicken pox. As this was a new policy, we also tested older children in order to cover the whole clinic. Evidence of immunity to VZV was determined by VZV IgG antibodies ≥ 0.9 IU/L (measured by the VIDAS VZV IgG enzyme-linked fluorescent immunoassay). We asked GPs to vaccinate patients with a negative result.
Results 178/232 (76.7%) patients ≥ 6 years were tested. 22 patients (12.4%) had no evidence of VZV antibodies and were therefore susceptible to chickenpox (Figure).
Conclusion In our paediatric CF population, the prevalence of VZV antibodies is similar to that reported for the general population. However, unlike the general population, children with CF are at greater risk of serious complications from varicella infection. In contrast to other groups of patients with chronic diseases whose treatment may result in immunosuppression, there are no UK-wide specific recommendations for VZV immunizations in CF. We suggest screening for VZV antibodies in children with CF at 6 years and offering vaccination for those found to be seronegative.
Vyse AJ et al. Epidemiol. Infect. 2004;132:1129-1134