Brazil is no stranger to mosquito-borne diseases, but some outbreaks tend to grasp media coverage and public attention more than others. The 2016 Zika virus outbreak made global headlines when it threatened much of Central and South America and endangered citizens and travelers alike. In the early months of 2016, the World Health Organization declared the Zika virus a public health emergency, alarming businesses, organizations, and international event-goers. The 2016 Summer Olympics in Rio de Janiero was at the forefront of the Zika virus outbreak and set a tone of severity for the virus that many still feel today.

Since the summer of 2016, Central and South American countries have seen an increase in mosquito borne disease outbreaks, including dengue fever, chikungunya, and the occasional case of malaria. Many experts attribute the recent increase of disease-carrying vectors to longer, hotter summers caused by climate change. Along with this increase, dangerous remote diseases have arisen once again. Yellow fever has reemerged as the next danger on the list.

Current Outbreak

Brazil’s yellow fever outbreak began in July 2017 and has been the largest outbreak to plague the country in decades. As of February 27, 2018, the World Health Organization has reported 464 confirmed human cases, including 154 deaths, with the highest concentration of cases in the Brazilian states of São Paulo, Minas Gerais, and Rio de Janeiro. As previously reported by VIGILINT, remote diseases have begun to inundate major global cities and Brazil’s metropolitan areas are not exempt. The densely-populated cities have become transmission grounds for yellow fever where unvaccinated citizens have exacerbated the spread. Some experts claim the disease is spreading “more than a mile a day” throughout the Brazilian regions. If the current rate continues, this outbreak could be the first major yellow fever epidemic in over 50 years. Travelers have been asked to refrain from traveling to areas of Brazil and the Centers for Disease Control and Prevention (CDC) has issued a Level 2 Alert calling for “Enhanced Precautions.”

Vaccination Challenges

Vaccination is the most important measure for preventing yellow fever contraction and spread, although this simple action has become one of the most challenging hurdles for health workers so far. The problem began last summer when the primary yellow fever vaccine manufacturer, Sanofi-Pasteur, declared a total supply depletion just as the Brazilian outbreak began. The company expects the supply to remain void until the end of 2018, putting those in yellow fever-endemic regions at a greater risk. In addition, some cities have reported stolen cases of vaccines from health clinics which has only worsened the shortage.

In January 2018, public health workers began a vaccination campaign to inoculate as many citizens as they could while attempting to preserve the stockpile. To do so effectively, health workers imposed a new protocol in which some citizens received a fractional dose while others received a standard dose. As of mid-February, 3.9 million people were vaccinated using fractional doses while 379,900 people were given standard doses. Experts believe that a smaller dose, usually one fifth of the regular dose, provides full immunity against yellow fever for at least 12 months; however, fractional dosing should not be used for routine immunizations.

In addition to the physical challenges posed by a vaccine shortage, there is also widespread public suspicion of the vaccine and of those who are administrating the inoculations. The “partial dose” strategy has caused citizens to become wary of this protocol and unconvinced of its preventative significance. Many also fear that a full dose of the yellow fever vaccine is more dangerous than contracting the disease itself; however, those fears are nothing more than rumors. According to Dr. Marques from a recent New York Times article, “about one recipient in 100,000 suffers a dangerous reaction like jaundice, hepatitis or encephalitis.” The statistics favor prevention over contraction in almost every case.

Brazilian health authorities will continue with the vaccination campaign in hopes of inoculating 95 percent of the population in a variety of affected cities. Public health workers will go door-to-door to ensure that recipients trust and understand the vaccine while reinstituting the same trust in public health officials.


As previously addressed, it is best to refrain from traveling to Brazil at this time, but if you must travel to the area, you should receive the yellow fever vaccine 10 days prior to your departure. It is important to plan and keep the vaccine shortage in mind. If pre-departure protocols are delayed, travel could be hindered or canceled entirely, inhibiting future business investments for international companies. Contact VIGILINT for location-specific yellow fever risk assessments and contingency plans.