There is a huge balance to be struck between vaccine efficacy and vaccine safety. Generally, a new vaccine goes through an incredibly rigorous procedure of safety testing, including multiple clinical trial steps to evaluate both the effectiveness and safety. For a disease that isn't posing an imminent danger or incredibly lethal, there is more time to be 100% certain of its safety. But for a disease that's currently posing a major threat and needs to have a therapy more immediately, the balance needs to be re-evaluated. With swine flu in 2009 in Europe, that threat was very real and decisions needed to be made within that context.

There is absolutely still a threshold of safety that must be met - there was no way a vaccine could bypass an animal model testing stage, for example. Or given such widespread distribution without small-scale tests. But frankly, the way vaccine safety testing works is that severe adverse events are 99.9% of the time already identified even before they reach any kind of human testing. It's that remaining 0.1% of the safety profile that may be overruled in the case of a pandemic, which the 2009 swine flu outbreak certainly was.

So with that in mind, if you're the minister of health weighing the increasing threat of the virus (by the end, there were over 17,000 cases and 2200 deaths in the EU alone) against the safety of a vaccine that is relatively speaking, pretty safe, what do you do? It's not an ideal situation. But that's also part of why flu is so fucking terrifying from a public health position. It has the ability to mutate well to new strains and cause massive pandemics, and each new strain needs a new vaccine to be developed every time.

Take Ebola, for example - certain vaccines have been distributed which haven't been as rigorously tested for safety as the average vaccine would have been. But the dire need and high risk of mortality allowed a few regulations to be loosened for slightly quicker disbursal of the vaccine. It absolutely could have some unseen adverse side effects, most likely in a very small percentage of cases - but the benefit of possibly preventing that much death outweighed the small chance of side effects. And still, it's very much an ethical question of whether the vaccine should have been provided or not given that it hadn't been through every safety stage.