The influenza virus mutates so fast that even if the vaccine is updated every year, there is no guarantee that the vaccination will cover all the seasonal epidemic. Influenza vaccination does not guarantee a 100% protection against influenza, and may also lead to side effects such as low fever in vaccinated people. Therefore, there is no need to be vaccinated against influenza.
The statement 'Only a very small number of people will have a systemic reaction after flu vaccine, and it can be relieved in one or two days, which is much lighter than flu symptoms' does not effectively refute the above conclusion.