It's a meningitis vaccine, responsible (along with Prevnar and other similar vaccines) for serotype replacement in vaccinated children, meaning that it kills a few types of bacteria which are then overrun with other, equally or more damaging kinds that can lead to different complications and illness. Here is an excellent dissection of these kinds of vaccines and why they are dangerous and, ultimately, futile: <a href="http://insidevaccines.com/wordpress/2008/01/31/sisyphus-and-the-conjugate-vaccines/#more-16" target="_blank">http://insidevaccines.com/wordpress/...cines/#more-16</a><br><br>
Also, it's been linked to Guillain-Barre Syndrome and even the CDC was investigating this link as recently as 2005: <a href="http://injury-law.freeadvice.com/drug-toxic_chemicals/menactra-vaccine-warning.htm" target="_blank">http://injury-law.freeadvice.com/dru...ne-warning.htm</a><br><br>
I'd skip it for sure and focus on boosting your 12-year-old's immune system through other, healthy means like good nutrition and supplements.