Herpes zoster (HZ) is prevalent in patients with Chronic Lymphocytic Leukemia (CLL) and affects younger patients who require chemotherapy. The risk of developing HZ increases in recipients of first and second line chemotherapy. In the time-varying analysis, there was a trend towards decreased infection in patients who received HZ vaccination.

Pharmacy records were used to identify patients who received treatment for CLL and HZ. HZ events were defined as patients with International Classification of Diseases 9th Revision (ICD-9) codes for HZ infection or prescriptions of acyclovir or valacyclovir at a dose of 1500 mg/day or higher or famciclovir at a dose of 1000 mg/day or higher without a diagnosis of Herpes simplex or Bell’s palsy, or an ICD-9 code and prescription above.

A cohort of 7155 patients with CLL was identified. A total of 2640 patients, and 1161 patients received first and second line chemotherapy respectively. HZ was detected in 1115 cases using ICD-9 codes, prescriptions, or both. Only 615 patients received HZ vaccinations. Patients with HZ were younger, had similar co-morbidities, and were more likely to get treatment for CLL. There was a trend for HZ vaccine to decrease the risk of developing HZ. When adjusting for age and co-morbidity, patients with CLL treated with first line chemotherapy had a higher risk of HZ compared to those never receiving therapy. Second line chemotherapy increased risk of HZ beyond first line treatment.