<p>Well it's really up to you..this one if different, that's what makes it new. It's a conjugate vaccine, vs. the normal polysacharide vaccine. Don't worry I won't elaborate. But, Menactra lasts longer and protects against more than the other one. However, it's really up to you, I personally would get the new one, but I work in the medical field and am around god knows how many antigens everyday..:)</p>