Yellow Fever Fatalities Reactivate in The Americas

As international travel rebounds in 2024, the Region of the Americas is expected to receive about 10% more visitors than in 2019. While this is excellent news for the tourism industry, disease outbreaks are also being reported.

In the Americas, there is a high risk of yellow fever outbreaks in 2024.

According to the Pan American Health Organization (PAHO), this mosquito-transmitted viral hemorrhagic disease poses a significant challenge to healthcare professionals. Any delayed recognition of yellow fever's signs and symptoms, which can often be nonspecific and may resemble other acute febrile syndromes, can lead to fatalities.

As of March 19, 2024, there have been seven confirmed cases of yellow fever, including four fatal cases reported in the Region of the Americas this year.

In 2023, four countries in the Region reported 41 confirmed cases of yellow fever, including 23 deaths. These countries include Bolivia (5 cases, including 2 deaths), Brazil (6 cases, including 4 deaths), Colombia (2 cases, including 1 death), and Peru (28 cases, including 16 deaths).

To reduce the 2024 outbreak, the PAHO/WHO reiterated recommendations such as these:

• Since the yellow fever vaccine is sufficient to confer lifelong immunity, universal vaccination in children in endemic countries at 12 months of age, 
• Administered an approved vaccine (Stamaril®) simultaneously with the measles, rubella, and mumps vaccine,
• Endemic countries should vaccinate populations in at-risk areas, reaching at least 95% coverage,
• Ensure all visitors to endemic areas are vaccinated at least ten days before arrival,
• And have a reserve vaccine inventory in case of outbreaks.

Jeri Beales, MSN RN with Destination Health Travel Clinic near Boston, MA, offered these comments to Precision Vaccinations regarding individuals with travel plans who need the yellow fever vaccine: "The data shared by PAHO reminds travelers and health care providers of the serious and often life-threatening risks of traveling to a yellow fever region without appropriate vaccination."

"All but two countries in South America have some risk of yellow fever disease, but no countries require the vaccine for passengers arriving from the United States."

"This leaves many travelers planning an adventure of a lifetime without realizing they will visit a yellow fever region."

"Speak to your provider's office or travel clinic at least several weeks before your planned trip to check if the yellow fever vaccine is needed."

In the January 22, 2024, issue of The Lancet Global Health, Jenny Schnyder and colleagues presented the results of a systematic review and meta-analysis assessing the long-term immunity provided by a single dose of a licensed yellow fever vaccine in people living in areas both endemic and non-endemic for yellow fever.

The authors wrote that in non-endemic areas, a single dose in adults resulted in high seroprotection rates over time (pooled seroprotection rate 94% [95% CI 86–99]), thus providing life-long protection for travelers.

And in endemic areas, adult vaccination resulted in somewhat lower seroprotection rates (76% [65–85]).

However, the studies from endemic areas were all conducted in Brazil and generally used a higher threshold for the definition of seroprotection, which could explain the differences.

However, lower seroprotection rates were found in children (47%) and in people living with HIV (61%), indicating a potential need for booster vaccination in these groups.

To date, there is no indication of waning protection in populations vaccinated in early childhood. But, the YF-VAX® should not be given to individuals who have experienced a severe allergic reaction to eggs, egg products, or any vaccine component.

In the United States, the YF-VAX vaccine is offered at certified clinics and travel pharmacies.