All vaccines have some short term side effects for some patients a few days afterwards. SO what? Vaccines over the decades have been very effective for the most part.
BUT, the biggest issues with vaccines are not short term, but potential long term side effects, (a few months to a few years after being innoculated) for many reasons, starting with these today having a very very very short rushed trial period (5 months instead of the usual >5 years), a completely new RNA/DNA configuration, and, hey, Moderna has never, ever, sold a product, ever, after 10 years of operations, until now.