Precisely 3 months before we set off our journey we began with vaccination. As South America is very large, some vaccines are only needed in some countries and some are only recommended. If you are going to travel to these locations, your best source of information would be CDC website - even the lady in the medical center was looking for information there. :)
http://wwwnc.cdc.gov/travel/
Basically, the only vaccine that’s required is Yellow Fever - without a certificate of vaccination they may deny your entry to Brasil. All of the others are optional, some of them highly recommended - Hepatitis A and B, Typhoid, Rabies. Probably the most infamous is Malaria - there is no vaccine against it, but you can protect yourself with antimalarials. You have to start taking them before going to risky areas and continue taking them during and after your stay - the duration vary depending on the type of the antimalarial. Note that none of them are 100% effective and you have to be a bit cautious and use other forms of protection as well (clothing, mosquito net, repelent). This is very important, as there is also Dengue fever - with no vaccination available as well. But do not worry - keep protected, use a bit of a common sense and you should be fine. :)
2017 Update: There are a few reports of a new Dengue vaccine Dengvaxia, already after clinical trials and approved in some countries. As we are now going to Mexico, which is in the listed countries, we will look into it there. http://www.sanofipasteur.com/en/articles/first_dengue_vaccine_approved_in_more_than_10_countries.aspx
As for us, we just had our first vaccination - typhoid and rabies. In a week, we are going again for second shot of rabies and in a month once again for rabies combined with yellow fever. As for Hepatitis - Ivan had been already vaccinated against A+B, but I had only two doses instead of three, so I went to get tested for antibodies - positive and strong, yay. :) (I was very pleased, as one combined vaccine costs around 50€ and you need three of those) As for antimalarials, we decided to buy them directly in South America, as the first leg of our journey we are not going to be in malaria-risk region.
Well, that's all for now. But from now on, we’ll try to write a new post each monday, so stay tuned and see you next Monday. :)