The simple, obvious answer is that they have no way of knowing for sure, and can only infer from knowledge prior vaccines that it's probably safe in 99+% of people.
Yeah, because all these prior vaccinations all came to the market a mere 10 months after the disease was discovered. No, they also weren't thoroughly tested in years of clinical trials. There's no difference between this vaccine and those that became for it.
The simple, obvious answer is that they have no way of knowing for sure, and can only infer from knowledge prior vaccines that it's probably safe in 99+% of people.
Yeah, because all these prior vaccinations all came to the market a mere 10 months after the disease was discovered. No, they also weren't thoroughly tested in years of clinical trials. There's no difference between this vaccine and those that became for it.