Varicella-zoster-virus-related hospital episodes increasingly coded concurrently for varicella and zoster, Australia, 2002–2021

After 2009, hospital episodes with principal diagnosis varicella, particularly in older age groups, frequently and increasingly have an additional zoster or postherpetic neuralgia code. Increased availability of real-time polymerase chain reaction testing and inadequate documentation in hospital medical records may have contributed to this.Implications for health information management practice:As hospitalisation data are extensively used to estimate disease burden and inform public health policy, the dual-coding issues identified require further investigation and mitigation.