Response to ‘Letter to Editor’: Herpes zoster after COVID-19 as a marker of long-term neuro-ophthalmic risk

Dear Editor, We write to thank Li and Lee for their thoughtful Letter to the Editor concerning our previous report on neuro-ophthalmic risks following herpes zoster (HZ) reactivation in coronavirus disease 2019 (COVID-19) survivors.1 Their clinical interpretation of absolute risk—noting a number needed to harm (NNH ≈ 200) for uveitis—provides an essential perspective.2 We concur that while these events are uncommon, their potential for irreversible visual loss3,4 supports a targeted, symptom-driven surveillance strategy rather than universal screening.2 Furthermore, we appreciate the authors’ insight that the occurrence of HZ following COVID-19 may reflect a state of broader systemic vulnerability. This aligns with emerging long-COVID frameworks characterized by chronic immune dysregulation,5 where HZ serves as a clinical sentinel of sustained neuro-immune vulnerability.6 Regarding the crucial concern of potential confounding by corticosteroid or biologic therapy, we conducted an additional sensitivity analysis excluding all individuals with documented steroid exposure to isolate the independent effect of post-COVID HZ (Table 1). In this subgroup, the associations remained remarkably consistent: the HZ-exposed cohort maintained a significantly higher risk for uveitis (adjusted hazard ratio [aHR] 3.01, 95% CI 2.56–3.65) and optic neuritis (aHR 2.03, 95% CI 1.52–2.71). These results mirror our full-cohort estimates, indicating that the observed risks are not primarily driven by the immunosuppressive effects of acute COVID-19 treatments.