Is there a vaccine for impetigo?

No. No, there is no vaccine for impetigo. Impetigo is a bacterial infection due to staph, and is treated with antibiotics.
No. Impetigo is a secondary bacterial infection caused by either a staph or strep infection. Currently there is no preventative vaccine. We can only hope....
It depends. If by pill and you mean a vaccine for impetigo as dr. Han correctly stated there is no vaccine. However if you mean a pill to treat an active infection, there are many antibiotics in pill form that will treat the bacteria (staph) that cause impetigo. More commonly however, anti-staph topical antibiotics such as bactroban (mupirocin) will be used to treat impetigo.