If you believe you have been injured by a vaccine, you may be eligible for compensation from a federal program called the National Vaccine Injury Compensation Program (or NVICP or, commonly, VICP). This is not a lawsuit, but a federal "no-fault" compensation program. In order to file a claim in the VICP, at least initially, you need to file a petition which describes what vaccine you believe caused your injury, when you received that vaccine, what injury you believe the vaccine caused, and when you first demonstrated symptoms of that injury.
With that petition, you should submit any evidence you have supporting what you claim in your petition. For example, whoever administered your vaccine, whether it was a corner pharmacy or your doctor's office, will maintain a record of what vaccine was administered (even what batch it was from) as well as the date you received it. This is often necessary to prove that you received a covered vaccine.
Also, if, for example, you experienced a shoulder injury related to vaccine administration (or SIRVA, one of the most common vaccine injuries), you may have seen your doctor within a short period of time after you received the vaccine. SIRVA's are quite painful and the pain often begins very soon after the vaccine is administered. Providing the medical record of your earliest doctor's visit related to that pain can show how quickly you experienced symptoms of your injury. You should also submit any medical records demonstrating the course of treatment for your injury. These records must also come from the "records custodian," who is the entity who maintains these records (such as your doctor's office). These records must also be certified by the records custodian.
Some vaccine injuries, like SIRVA, also happens to be what are known as "table injuries." A table injury is a certain injury which, if it occurs within a certain amount of time after vaccine administration, can make you eligible for compensation without having to prove the vaccine caused your injury. For table injuries, that the vaccine caused your injury is presumed. These injuries and the vaccines related to them are listed here:https://www.hrsa.gov/sites/default/files/vaccinecompensation/vaccineinjurytable.pdf.
If your injury is not listed as a table injury, things get a bit more complicated. In that case, you will need to prove that the vaccine caused your injury and - in most cases - that requires a medical expert.
In either case, ensuring that you have everything you need to file your claim can be a complicated process. For that reason it is a good idea to obtain the assistance of an attorney with experience in the VICP.