Redness, swelling, hard nodules and itchiness after vaccination with New Crown vaccine may be caused by adverse drug reactions or the depth and speed of injection, and usually do not require special treatment. It is recommended that when there is redness, swelling, hard nodules and itching at the vaccination site, do not rub it with your hands, and disinfect it with iodophor or apply hot compresses to help relieve it. 1. Adverse drug reactions: Since the new crown vaccine is a vaccine made by inactivating and attenuating pathogens through physical or chemical methods, there is still a certain degree of toxicity, which may cause a few people to have some transient and mild body reactions due to individual differences, such as redness, swelling, hard nodules, itching, pain and other local reactions at the vaccination site, or weakness. Local reactions such as redness, swelling, nodules, itching and pain at the vaccination site, or systemic reactions such as malaise, headache and fever may occur in a small number of people due to individual differences, while abnormal reactions such as acute and severe allergic reactions are rarely seen. It is recommended to stay in the hospital for 30 minutes after vaccination and leave again when there are no uncomfortable symptoms. 2. Injection depth and speed: When the new crown vaccine is injected too deeply and too fast, it will cause the drug solution not to be absorbed into the blood by the tissue in time and stimulate the local muscle contraction, resulting in redness, swelling, hard nodules and itching at the vaccination site. This is a normal reaction after vaccination and is not a cause of excessive stress. If the symptoms do not disappear after a long time and are accompanied by other uncomfortable symptoms, it is recommended to go to the hospital for examination and treatment.