Herpes zoster epidemiology during and after the COVID-19 pandemic: A 5-year retrospective study from primary care in Poland

BACKGROUND: Herpes zoster (HZ) is caused by reactivation of latent varicella-zoster virus and affects 25-30% of individuals, with the highest incidence in adults aged ≥50 years and a lifetime risk exceeding 50% after the age of 85. Its most common complication is postherpetic neuralgia (PHN), i.e., persistent neuropathic pain. Reports of increased HZ incidence during or after SARS-CoV-2 infection suggest potential epidemiological associations requiring further investigation. OBJECTIVES: Our goals were to evaluate the incidence of HZ and its complications during the pandemic and the post-pandemic period in primary care settings in Poland. MATERIAL AND METHODS: We conducted a retrospective multicenter study in 20 primary care clinics in Poland, covering 43,949-81,091 patients from 2020 to 2024. Incident HZ cases and complications (PHN, herpes zoster ophthalmicus (HZO), HZ oticus, and disseminated HZ) were identified, and demographic data, including place of residence, were collected. Statistical analyses included χ2 or Fisher's exact tests, Student's t-tests or nonparametric equivalents, odds ratios (ORs) with 95% confidence intervals (95% CIs), and receiver operating characteristic (ROC) analysis to assess age-related risk of prolonged symptoms. RESULTS: A total of 570 HZ cases were recorded from 2020 to 2024. Incidence ranged from 1.61 to 2.14 per 1,000 persons and increased with age, reaching 6.57 per 1,000 in individuals aged ≥80 years. Patients aged ≥71 years had higher odds of developing PHN (pain persisting for >90 days) than younger patients (OR = 4.47; 95% CI: 2.30-8.67; p < 0.001). Older adults were also more likely to develop HZO (p = 0.001). Rural incidence was significantly lower during the pandemic than in the post-pandemic period (p = 0.005), with no significant differences in urban or semi-urban areas. CONCLUSIONS: The risk of HZ, PHN, and HZO rises with age. During the pandemic (2020-2021), rural incidence was significantly lower than in the post-pandemic period (2022-2024). The study provides updated data on HZ epidemiology in Poland and highlights the impact of the COVID-19 pandemic on healthcare access and HZ reporting in rural areas.