Reactive Axillary Lymphadenopathy Among Different COVID-19 Vaccines: A Retrospective Study in Breast Sonography.

Background/Purpose: During the coronavirus disease 2019 (COVID-19) outbreak, reactive lymphadenopathy after vaccination is a major concern in breast sonography, especially for patients with a history of breast cancer. The state-of-the-art literature on clinical and sonographic findings either examines a small volume of cases or limited types of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. This study is aimed at providing vast clinical information to facilitate breast sonographic examination for participants who underwent recent SARS-CoV-2 vaccination. Methods: Among different SARS-CoV-2 vaccines in the Asian Taiwanese population, reactive axillary lymphadenopathy was investigated through breast sonographic findings and clinical data analysis. The sample included participants with recent vaccination by different brands approved in Taiwan, such as the AstraZeneca ChAdOx1 (AZ) vaccine, Moderna mRNA-1273 (Moderna) vaccine, and Pfizer-BioNTech BNT162b2 (BNT) vaccine. Results: A total of 291 participants received the AZ vaccine, 154 received the BNT vaccine, 222 received the Moderna vaccine, and 422 were nonvaccinated during the study period. The incidence rate for axillary reactive lymphadenopathy was 10.9, 21.3, 21.4, and 0.6, respectively. No incidence of malignancy was reported during the 6-month follow-up period. The AZ vaccine, which is a virus-vector vaccine reported a lower incidence rate than mRNA vaccines. We also found lymphadenopathy may last for more than 1 month after vaccination in this study. Conclusion: The study results provide additional supporting information for the management suggested by the recently updated revision of the Society of Breast Imaging guideline pertaining to lymphadenopathy diagnosis of SARS-CoV-2 vaccine-related ipsilateral lymphadenopathy and screening of mammograms.