The Changing Trends in the Incidence and Clinical Presentation of Immunobullous Disorders Before and During the COVID-19 Era in a Tertiary Healthcare Centre in Andhra Pradesh.

Background Autoimmune immunobullous disorders (AIBDs) represent a heterogeneous group of chronic blistering dermatoses mediated by autoantibodies against desmosomal and hemidesmosomal adhesion molecules. The COVID-19 pandemic has generated significant interest in the interaction between SARS-CoV-2 infection, vaccination-related immune modulation, and the clinical behaviour of autoimmune diseases. Objective This study's primary objective is to compare hospital-based temporal trends in the frequency, subtype distribution, and clinical presentation of AIBDs before and during the COVID-19 era in a tertiary healthcare centre in Andhra Pradesh. Secondary objectives included evaluation of changes in age at onset, sex distribution, mucosal and nail involvement, recurrence, and the emergence of atypical clinical morphologies requiring histopathology and direct immunofluorescence (DIF) for definitive diagnosis, as well as identification of independent predictors of subepidermal AIBD subtypes using multivariate logistic regression. Methods A retrospective observational analysis was performed on 42 histopathology and/or DIF-confirmed AIBD cases. Eighteen cases were recorded in the pre-COVID period (January 2018-December 2019) and 24 during the COVID era (January 2020-November 2023). Demographic trends, morphological patterns, mucosal involvement, anatomical distribution, severity, recurrence, and atypical phenotypes were compared between the two cohorts. Results A notable increase in overall incidence was observed during the COVID era (57.1%). Disease onset occurred at a younger age during COVID (mean 47.8 years) compared with the pre-COVID period (mean 53.6 years). Mucosal involvement increased from 33.3% pre-COVID to 50% during COVID. The COVID cohort exhibited higher recurrence rates and atypical morphology, including confluent mucosal and oesophageal lesions in epidermolysis bullosa acquisita, a "cluster of jewels" configuration and nail dystrophy in bullous pemphigoid, and healing with scarring and milia. These atypical patterns required more frequent reliance on biopsy and DIF for achieving a definitive diagnosis, as classical clinical presentation alone was insufficient. Conclusion The COVID-19 era was associated with both increased hospital-based case frequency and altered clinical expression of AIBDs, characterised by younger disease onset, greater mucosal involvement, and diagnostically challenging phenotypes. Possible contributors include post-COVID immune dysregulation, vaccination-associated immune activation, psychological stress, and lifestyle changes. Intensified clinical vigilance, early DIF-based confirmation, and timely initiation of steroid-sparing immunomodulatory therapy are essential to optimise outcomes in the evolving post-pandemic context.