Read this to see how vaccines are safety tested: TGA Vaccine Regulation Overview
(TL/DR: tested by the manufacturer, not an independent body or a government body, but by the manufacturer who stands to make untold millions from the acceptance of one vaccine into the national schedule. Not duplicated or validated, not even reviewed, simply viewed by an Advisory Committee and ratified. Not tested in combination with the other vaccines already in the schedule. Privately tested and risk assessed in the hen house, by the fox.)
The best possible outcome is that epidemiologically (statistically across the population) a vaccine can be shown to cause a minimal percentage of AEFIs – adverse events following immunisation.
Then, once they are added to the schedule, there’s the question of individual safety – actual AEFIs to consider.
The information no-one wants to acknowledge, is that adverse reactions to vaccinations happen. They, as the epidemiological (AKA ‘safety) data states, are uncommon. They are not, by any stretch of the imagination, statistically rare. Especially when you consider how few are reported and that even fewer are acknowledged.