Well you don’t know anyone who got a reaction yet. The reason vaccines normally take so long to be tested is because we need to see the long term data. The lady I know of who got a blood clot in her foot, something like that could rly flare up at any time really it could take a month or a few years to show up

The cdc site has a link that disputes this point, here is the excerpt:

Long-Term Side Effects Are Unlikely

Serious side effects that could cause a long-term health problem are extremely unlikely following any vaccination, including COVID-19 vaccination. Vaccine monitoring has historically shown that side effects generally happen within six weeks of receiving a vaccine dose. For this reason, the FDA required each of the authorized COVID-19 vaccines to be studied for at least two months (eight weeks) after the final dose. Millions of people have received COVID-19 vaccines, and no long-term side effects have been detected.

Full link is: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/safety-of-vaccines.html