Those travelling on short notice also opt to buy the card, since it takes 10 days after immunisation to develop immunity and for the certificate to be valid. So, some people backdate the immunisation date to show they received the vaccine ten or more days earlier.
However, new technology now makes it easier for health authorities in every country to detect this fraud. The consequences can be serious and can lead to either deportation or prosecution. Yellow fever affects 35 countries in Africa, and the WHO's latest report says it attacks 400 million people globally every year.
Without proper treatment and in the absence of preventive measures, it can cause serious negative health consequences, including death.
Moses Mwangi, an epidemiologist and vaccine specialist says it does not require a doctor's consent to get vaccinated, you simply walk into a designated vaccination centre and ask for the jab, Dr Mwangi explains.
This applies to all vaccines, not only for yellow fever. According to Professor Charles Chunge, the Director of the Centre for Travel and Communicable Diseases, yellow fever can range from a mild illness to a potentially fatal disease. While most infected individuals experience mild symptoms, it can progress and cause severe problems, including internal bleeding.
Other symptoms of yellow fever are body ache, back pain, nausea, vomiting, fatigue, fever, chills, severe headache, weakness, yellow skin, yellow eyes, jaundice, bleeding, shock, and organ failure.
"These symptoms appear about four days after infection, and 15 per cent of symptomatic patients will develop severe disease. Most will recover, but bouts of yellow fever recovery may take weeks or months," says Professor Chunge.
The disease is caused by bites from Aedes mosquitoes. To control the disease, Dr Mwangi explains that home-based preventive measures as well as pharmacological interventions are essential.
The use of insect repellent every four hours is necessary. Clearing bushes and destroying stagnant water containers around homes should be carried out. Wearing thick and protective clothing, which mosquitoes cannot penetrate, is also advised by Professor Chunge.
Additionally, those with underlying medical conditions such as tuberculosis, HIV/AIDS, and diabetes should seek medical advice before getting vaccinated. Experts advise that pregnant women and breastfeeding mothers may have an increased risk of side effects from vaccines and should, therefore, also seek medical advice before immunisation.
The cost of treatment is about Sh10,000 to buy a 500ml bottle of oral medicine or concoction.
This is too expensive for ordinary citizens who live on less than one dollar a day or below the poverty line.
Doctors say there are no specific antibiotics for yellow fever because it is a viral infection, not a bacterial one. Antibiotics are only effective against bacterial infections.