Libertine

It's not actually a "drug created on the fly".

Creating different vaccines fairly often works in roughly the same way. When you're merely talking about different strains of a specific subtype of virus, the process is almost exactly the same.

There are a few possible risks with vaccines: a virus that has not been inactivated, adjuvants (agents to help provoke a reaction from your immune system) that turn out to be toxic, and contamination.

Now, the first risk is a rather small one. If something would go wrong there, it would be detected very quickly and the effect would essentially be that you immediately got the disease you were being vaccinated against - the reason it would be detected so quickly.

The third risk is a small one, too. It's essentially the same kind of risk you run when getting IV fluid, or even when you something. Obviously, the standards vaccines are held against are quite high, so you'd typically run a bigger risk getting a hot dog from a corner stand or taking some vitamin pills with breakfast.

Adjuvants, however, could be somewhat of an issue.

They essentially serve to help provoke a reaction by your immune system, helping your body in recognizing the deactivated virus as a potential threat which should be remembered. More practically speaking, they usually induce a tiny local inflammation, which triggers an immune response in the place where the inactived virus is also present, causing your body to basically associate the virus with disease.

Obviously, then, they can't be entirely harmless - after all, don't they trigger a response from your immune system?

The good news is that they've been researched quite well during the past few decades, potentially dangerous ones are no longer being used, and the ones that actually are used with flu vaccines (where it's already known what kinds are most likely to be useful - something that varies per type of virus) have been well-tested.

Moreover, they're not the scary, dangerous materials the alarmists make them out to be. For example, what's often used are aluminum salts, which are also present in your deodorant, your food, etc. The immune reaction being provoked with the vaccines is comparable to that which you would see in a woman who cut herself a little while shaving her armpit and then applied deodorant - a small bit of redness and swelling.

There are some more advanced adjuvants, such as certain enzymes found in specific viruses, but those are equally safe, and have been tested extremely well before being allowed on the market.

Basically, if on some given day you cut yourself shaving, apply deodorant and aftershave to your body, eat a few meals, come near one or two sneezing people and take some vitamin pills, you're exposing yourself to the same type of "risks" that taking a vaccine exposes you to - larger ones, actually, because the sneezing people have a realistic chance of infecting you with something.

Also, keep in mind that with large groups of people, it's inevitable that some things happen - with or without vaccination. Vaccinate a million people, and you will inevitably see a number of them suffer from unexplained or rare diseases in the months that follow. Just because with any given group of such a size, there will be a few people developing unexplained or rare diseases in the timespan of a few months no matter what you do.

Hell, among some ethnic groups sudden death during sleep occurs about 40 times per 100k young, healthy population per year (google "sudden unexplained death syndrome"). In a group of a million, that's 33 deaths per month, or slightly over 1 per day - which gives a rather large chance that someone would suddenly die the day after a vaccination if 1 million were vaccinated, despite the vaccination having absolutely nothing to do with it. And that's just one syndrome

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