I was in South Africa in July of 2013 on an all-expense paid trip by South Africa Tourism board in the company of other travel agents. Our yellow cards were requested at the immigration point into Johannesburg. To our amazement, a guy among us was eventually deported right from Johannesburg because the Yellow fever vaccine he took was not up to Ten days before he left Nigeria!

The Carte Jaune or Yellow Card is an international certificate of vaccination. It is issued by the World Health Organization. It is recognized internationally and may be required for entry to certain countries where there are increased health risks for travelers. 

Yellow fever is a viral hemorrhagic fever transmitted to humans through the bite of infected mosquitoes. This can become a deadly disease, especially for people who have not been vaccinated.

A single dose of the yellow fever vaccine, however, provides lifelong protection against the disease. The vaccine gives immunity within 30 days and is effective for 99 percent of persons vaccinated. This lifetime validity applies automatically to all existing and new certificates, beginning 10 days after the date of vaccination.

The World Health Organisation (WHO) recommends that to travel to countries where there is evidence of persistent or periodic yellow fever virus transmission, people need to be vaccinated and obtain the yellow card.

Also known as the International Certificate of Vaccination or Prophylaxis (ICVP), the yellow card is usually requested at immigration points.

Without it, travellers are not allowed into or out of countries prone to yellow fever. Africa falls within the yellow fever endemic zone.

Countries like South Africa and Ethiopia strictly look out for the yellow fever vaccination cards of travelers coming from high-risk countries before allowing them into their countries.

It is advisable to get vaccinated and obtained your yellow card as soon as possible to avoid issues or delay at immigration.