Yellow Fever—The Next Global Health Crisis?

In early April the World Health Organization (WHO) announced that most provinces in Angola have experienced a yellow fever outbreak. Now, scientists are calling this the country’s worst epidemic since 1986, urging WHO to take action.

The Threat of Yellow Fever

With a total of 2023 suspected cases and 258 deaths since it began in December 2015, Angola’s yellow fever outbreak is quickly spreading to other countries, including China, the Democratic Republic of Congo, and Kenya, as well as neighboring countries. In a recent article published in the Journal of the American Medical Association, study authors, Daniel Lucey, MD, MPH, and Lawrence O. Gostin, JD, state, “Similar to other recent epidemics, quick and effective action to stop the spread of yellow fever is the responsibility of the world’s health community.”

It was noted that a shortage in vaccines can result in a “health security crisis” if the virus spreads throughout Africa, Asia, and the Americas. The authors warn that in the Americas, where Aedes mosquito populations are high, yellow fever can spread as quickly as Zika, Dengue, and Chikungunya. Furthermore, Asia has never before experienced a yellow fever epidemic and may not be well-equipped to handle an outbreak.

On April 22, the Pan American Health Organization declared an epidemiological alert for yellow fever in South America. The study authors warn that if WHO does not move forward with an emergency response plan that involves “a surge in vaccine production,” the current yellow fever outbreak can result in a global epidemic similar to that of the Ebola virus and the ongoing Zika crisis.

Yellow Fever Vaccine Shortage

A vaccine for yellow fever can provide lifetime protection against infection; however, individuals older than 60, infants, pregnant women, and those with severe immunodeficiencies or severe egg allergies, who do not live in or are not traveling to areas where the virus is widespread, should refrain from receiving vaccination.

Thus far, more than 7 million individuals have been vaccinated against yellow fever in Angola alone. Earlier in May, the Democratic Republic of Congo announced that 2 million individuals residing in Kinshasa and Kongo Central are to be vaccinated against yellow fever, since local viral transmission is expected to hit these areas.

Study authors urge WHO, which currently serves as the Secretariat for the International Coordinating Group (ICG) on Vaccine Provision for Yellow Fever, and its partners—the United Nations Children’s Fund (UNICEF), the International Federation of Red Cross and Red Crescent Societies, and Doctors without Borders—to take action to prevent a vaccine shortage. Although ICG preserves a vaccine supply in case of a global pandemic, the authors expect that a vaccine shortage is inevitable if the virus spreads to other countries and regions of the world. They note that, “surge capacity is currently limited because specific pathogen-free chicken eggs are needed to produce the vaccine.”

Taking Action Against Yellow Fever

The study authors believe that WHO can implement the Emergency Use Assessment and Listing (EUAL) procedures, previously used to combat Ebola, to “safeguard the yellow fever vaccine supply.” Furthermore, international experts recommend using only one-fifth of the usual vaccine dose on Angolan residents in order to “avert acute shortages” of the vaccine supply in case the virus spreads internationally. Nonetheless, this would not only go against vaccine regulations, it might also alter the vaccine’s duration of effectiveness, particularly in children. However, the authors believe that action should be taken now, rather than after yellow fever becomes a global threat and a vaccine shortage becomes a reality. “Given the world’s viral health security interests, the WHO’s director-general should use EUAL procedures to authorize a reduced vaccine dose to control the epidemic in Angola,” they stated.

The authors acknowledge that an emergency committee is needed before WHO can declare yellow fever to be a public health emergency of international concern. As such, and due to the impending vaccine shortage the authors believe could become a reality, they strongly recommend that WHO convene an emergency committee as soon as possible. They further recommend that, if the emergency committee does not deem the threat of yellow fever to be a global crisis, EUAL be implemented to reduce the yellow fever vaccine dose in order to prevent a shortage in supply. Furthermore, the authors recommend that WHO should meet with vaccine manufacturers “to catalyze a surge in production; incentivize and coordinate innovation in research and development for non—egg-based yellow fever vaccines; [and] coordinate mosquito vector control for yellow fever, benefitting also prevention measures for the ongoing Zika virus epidemic.”

In contrast to WHO’s response time to the threat of Ebola and Zika, the organization has already started taking action against the threat of yellow fever. Nonetheless, the authors believe there should not be a need to form an emergency committee each time there is a health threat of these proportions. They recommend that WHO institute a “standing emergency committee” so as to counsel the director-general on which steps are to be taken: declare an international health threat, take action to prevent a global health crisis, or both.

The study authors further noted that the UN believed that the Ebola crisis was a “preventable tragedy.” In the High-level Panel on the Global Response to Health Crises, it was noted that “if the WHO does not successfully reform, the next major pandemic will cause thousands of otherwise preventable deaths. This may be the last opportunity to ensure that the WHO is empowered to build an effective emergency preparedness and response capacity with the necessary political leadership. Another failure to perform may necessitate consideration of alternate UN institutional response mechanisms.”