Wirelessly posted (BlackBerry8100/4.2.0 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/100)

I once needed a vacc proof. Easily bought the 'proof' for $100usd in nairobi.

seriously, they will not notice. Don't worry about it if you aleady have a visa.

you make good points. too bad the op cant just show THIS to the immigration officer in hopes they understand such things.

Last time I was in Africa the truck driver had pre-made stamps to fake vaccination cards. It seems some of the border crossings could give you trouble if you didn't have your smallpox shot. (Trouble as in needing bribes, not trouble as being turned back.) The thing is, this was 1982--the shot was unobtainable.

My straight forward advice is - you are not likely to have a problem when you come directly from the US. The worst thing they can do is have you take the vaccination at the airport (make sure they use a new needle or bring one with you.)

The longer answer is that 7 years ago i crossed the border from Brazil to Bolivia. While I knew that a yellow fever vaccination is required to enter bolivia from brazil, I did not take it too seriously (or thought that the Bolivians won't take it seriously...) As I reached the border I realized that I was wrong - the bolivians sent back everyone with the vaccinations. It wasa real middle of nowhere crossing and I was desperate not to stay there for another day so I took a pen and handwrote on my vaccination card "Yellow Fever Vaccine, Name of city and date". The immigration officer took a look, tried to trick me and asked me where I got the vaccination (LOL) I told him the name of the city and he let me pass through. Funny enough, there were 6 guys behind me (same nationality as myself) that really took the vaccination but their card didn't say Yellow fever vaccine, but the name of the active material in the vaccine. The Bolivian that didn't know what it was didn't let them through and sent them back to Brazil to get a vaccine.

I wasn't aware of this yellow fever twist in Brazil, but a friend of mine once went to Turkish North Cyprus and had his passport stamped there, and was denied entrance to Greece for merely having been there, and that was a year later!

This has nothing to do with immunizations. It's a diplomatic issue (to make things simple): the TRNC is not recognized by the Greek half, so they refuse entry if you have TRNC stamps in your passport.

"that doesn't stand in the way for any immigration officer to harass me"

Questioning you about your activities is NOT harassment. It's called doing their job.

To the OP, you should probably be doing more research before you enter such countries. Remember, you're going to a place where they require yellow fever vaccinations and you don't have one. Your worry shouldn't be about your passport, it should be about not catching yellow fever.

According the Brazilian Embassy you are wrong.

Vaccination
YELLOW FEVER INTERNATIONAL IMMUNIZATION CERTIFICATE
A yellow fever vaccination is mandatory if applicant traveled within the last 90 days to any of the following Countries: Angola, Benin, Bolivia, Burkina Faso, Cameroon, Colombia, Ecuador, French Guyana, Gabon, Ghana, Gambia, Guinea, Liberia, Nigeria, Peru, Sierra Leone, Sudan, Democratic Republic of Congo (ex-Zaire) or Venezuela.

A yellow fever vaccination is advisable if applicant’s destination in Brazil includes any of the following States: Acre, Amapá, Amazonas, Goiás, Maranhão, Mato Grosso, Mato Grosso do Sul, Pará, Rondônia, Roraima, Tocantins and the Federal District.
http://www.anvisa.gov.br/eng/pab/travelers/index.htm#

This is what TIMATIC says:

Well, Brazil states 90 days on their website, and at the Brazilian consulate in Ecuador, I was also told that I had to have a yellow fever vaccination for entering within 90 days, even from the US.

Yes, I saw that too, but TIMATIC is funded by IATA member airlines, and is generally very accurate (at least in practical terms). If there was an actual case involving deportation (at the carrier's expense) and/or a fine, I am pretty sure that that info would have been revised really fast .

[I decided to remove this post.]

I'm always a bit confused when posters comment about being held up by U.S. immigration for visiting X or Y country. U.S. immigration is icy and unwelcoming, for sure, but no one has ever cared where I'm coming from, even when it was, for instance, Yemen in the dead of summer with a three-week beard!

Actually, coming back from North Korea (on a Beijing-Newark flight), with no record of being there aside from the card I filled out on the flight was no problem (they don't stamp the passport, so there was simply a China exit and another China entry stamp a few days apart)! I just always treat border agents civilly; never had a problem.

Thanks for all the advice. I was pretty confident there would be no problem based on the reponses and especially the fact that I was coming in from the US, not Colombia. The agent didn't page through my passport at all, and there were no questions re: Yellow Fever countries on the entry paper work.

As for getting the shot for my own safety, I was in Medellin, Colombia, at a medium altitude, in an upscale neighborhood. I never heard or felt a mosquito. No one I met ever mentioned mosquitos or Yellow Fever. I have friends that have been many times, including to other, more remote places. They had never heard of the requirement. Just because Brazil has a specific requirement, doesn't mean that my particular trip put me at risk. If I thought I was at risk, I would have gotten the shot, even if I weren't going to Brazil.

As for getting it in one day, I barely had time to finish up work, pack, pick up a few things and make personal arrangements. My guess is that getting the shot would have involved hours of driving and hours of waiting. I'm in a far south suburb.

By getting the advice from Flyertalkers, I felt pretty confident that I wouldn't have a problem. This is a one time problem for me, as I'll check more carefully in the future.

Thanks again for all the responses.