That's a possibility, but we can ask the same question about big pharma's too, no? how do we know that they are not lying or hiding some "minor" information from us in order to "get benefits"? You think they are 100% honest and sincere?
A bee sting can kill people but a vaccine can NEVER cause any kind of harm to anyone?!?!?!? really?
They (and you too) don't give a shit if vaccines can cause harm in one out of 1.000 people or kill 1 out of 100.000 (Those numbers are made up by me but you get the picture)
The truth must be told and the public must know that there are some serious risks no matter how small the chances are.