Background <p>Capsular contracture, a prevalent complication following breast augmentation, is characterized by pain, implant distortion, and often necessitates explantation. While its multifactorial pathogenesis involves bacterial biofilms and implant characteristics, the influence of immune activation, particularly in the context of COVID-19 infection and vaccination, remains underexplored. Growing evidence suggests COVID-19 vaccination can trigger immune-mediated reactions, including delayed inflammatory responses to dermal fillers. Given that capsular contracture is a fibro-inflammatory response, this study investigated whether COVID-19-related immune activation influenced the time from breast implantation to explantation due to severe capsular contracture.</p> Methods <p>This retrospective cohort study analyzed patients from a single private practice who underwent breast implant removal due to Baker grade III or IV capsular contracture. Two historical cohorts were compared: Cohort 1 (pre-pandemic: January 2016 – December 2019) and Cohort 2 (post-pandemic: January 2021 – December 2024).The primary outcome, time from implantation to explantation, was analyzed using Kaplan-Meier survival curves, log-rank tests, and a multivariate Cox proportional hazards model, adjusting for confounders. Ethical approval was obtained (CAAE: 35154720.2.0000.5330).</p> Results <p>A total of 115 patients were included (47 in Cohort 1, 68 in Cohort 2). Baseline characteristics were comparable between groups. The time from breast implantation to explantation due to Baker grade III/IV capsular contracture was significantly shorter in the post-pandemic cohort (4.9 ± 1.3&#xa0;years) compared to the pre-pandemic cohort (8.2 ± 1.5&#xa0;years, <i>p </i>&lt; 0.001). The Kaplan-Meier estimated median time to explantation was 5.0&#xa0;years (95% CI: 4.6–5.3) for the post-pandemic cohort versus 8.0&#xa0;years (95% CI: 7.6–8.4) for the pre-pandemic cohort (<i>p </i>&lt; 0.001). Multivariate Cox analysis showed a hazard ratio of 2.3 (95% CI: 1.5-3.5, <i>p </i>&lt; 0.001) for earlier explantation in the post-pandemic cohort, independent of confounders. No significant differences were found in the proportion of Baker IV contractures or primary complaints.</p> Conclusion <p>While this study does not establish causation, the observed reduction in the time to explantation in the post-pandemic cohort compared to the pre-pandemic cohort suggests that external factors, including potential immunological responses to the COVID-19 vaccine or infection, may have influenced the progression of capsular contracture. This information is relevant for clinical practice and has implications for patient management, informed consent, and medicolegal assessment of implant-related complications.</p> Level of Evidence III <p>This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors <a href="http://www.springer.com/00266">www.springer.com/00266</a>.</p>