The internet is full of idiots, that much is for certain.
But sometimes, when the seasons start to turn and the planets align just right, a Learned comes along to take even just one of these internet idiots to task, and we are left to rejoice that it isn't just us, that we aren't just taking crazy pills, and that there are other sane, normal people out there who understand the beauty of rational thought.
This is one of those times...
According to PolicyMic, when a particular breed of internet idiot that specifically harps about the dangers of vaccination posted an image of the ingredient list to an influenza vaccine to Tumblr, after having circled some of the "scarier" words, which gained momentum from others who don't understand the finer points of causality, a professed home health care worker who actually knew what they were talking about decided to specifically point out all the ways in which this anti-vaccinationist was, in fact, an internet idiot.
"Ok, lets break this down nice and simple.
Formaldehyde is from the purification of the vaccine. 99.9% of which is removed. The reason it doesn't give a dosage is the ammount is so minuscule that it can't be measured without going into picograms. That's one trillionth of a gram. You breathe in more formaldehyde by driving down a busy road than in a vaccine.
Thimerosal is NOT elemental mercury, It is a molecular compound made up of carbon, hydrogen, mercury, sodium, oxygen, and sulfur. This is used as a preservative for the vaccine. Thimerosal is used in a variety of other things, like tattoo ink, facial creams, nasal sprays. It's toxic to humans only in fairly large quantities but highly toxic to aquatic born organisms like infectious bacteria. In short, it makes sure you don't get salmonella from a stray bacteria from the chicken embryos.
As for the dosage of the Thimerosal. That is the most laughable point in this post. It says 25 mcg, that's micrograms, or one millionth of a gram. To put this in perspective, a dollar bill weighs roughly 1 gram, the average human eyelash is around 80-90 micrograms. The box also says that it contains a 5ml (milliliter/cc) vial which leads me to my next point.
A little simple math and we find out that 25 mcg = 0.00003 ml and a little more math we find that 0.00003 ml is 0.00006% of 5 ml. Let me put this another way. By the age of 5, an American child weighs about 50-55lbs and their body contains 55 mcg of Uranium. I don't see any kids running around with radiation sickness, so I think they're safe with a preservative in them.
TL;DR: This is like saying you don't want your child eating their baked birthday cake because raw eggs were used to make it and you don't want your child getting salmonella from it."
Now, let us all rejoice. Hallelujah, Hallelujah.