Redness, swelling and hardness at the injection site after vaccination is a very common adverse reaction. Because the vaccine preparation also contains some components that may irritate the soft tissues of the skin, it is relatively normal that the injection may cause local redness and swelling. Generally, after 3-5 days, the lumps will gradually subside. After vaccination, first of all, you should pay attention to avoid contamination of the injection site, and try not to take a shower within 24 hours to avoid contamination of the injection site and infection of the skin and soft tissues. In addition, the redness and swelling of the lumps can be treated by applying hot compresses, which can promote blood circulation and eliminate the lumps. You can also apply potato slices to the red, swollen and hard areas to reduce swelling. Also note that if there are other symptoms such as fever or skin breakdown, you need to go to the hospital for timely examination and treatment.