Severe breast nodules after the New Crown vaccine may be caused by stress. Adverse reactions to the New Crown vaccine usually do not include breast nodules; while breast nodules may be caused by diseases such as breast cysts, breast fibroadenomas, and intraductal papillomas of the breast, which are related to mental factors and endocrinology to a certain extent. The common adverse reactions after receiving the New Crown vaccine are mainly mild pain and swelling at the injection site, in addition, the vaccinated person may also experience mild fever, fatigue, muscle aches and pains. Vaccination with the new crown vaccine does not usually cause the symptoms of breast nodules to become severe, so the symptoms of breast nodules becoming severe may be related to stress. Breast nodules are commonly caused by breast cysts, fibroadenomas, and intraductal papillomas, etc. When patients with these diseases are stressed after receiving the New Crown Vaccine, it leads to endocrine disorders, which can lead to the symptoms related to breast nodules becoming severe. Please relax after the vaccination, and if you are diagnosed with breast nodules, please follow the doctor’s instructions for regular checkups or treatment.