Yellow Fever Vaccination Campaigns May Be Key to Eliminating Epidemics Worldwide

Yellow fever continues to make headlines as a massive outbreak in Brazil rages on. Last month, the number of confirmed cases of the disease tripled in number, and Brazil set out to launch the “world’s largest vaccine campaign” using a fractional dose of the yellow fever vaccine.

As of January 23, 2018, Brazil’s Ministry of Health has reported 130 confirmed cases of yellow fever since July 1, 2017; 53 of these individuals have died.

The sharp increase in cases has been noted mainly in the states of São Paulo and Minas Gerais. As such, the Minas Gerais government declared a “public health emergency situation” at the end of January, after 22 cases of the disease were confirmed and 15 of those individuals died.

Since September 2017, national authorities have been focusing their efforts on intensifying vaccination activities. On January 25, 2018, Brazil launched a mass immunization campaign set to deliver fractional doses of the yellow fever vaccine to those living in 69 municipalities throughout the states of Rio de Janeiro and São Paulo.

“Fractional dosing, also known as dose-sparing, is a way to extend vaccine supplies, protecting more people and reducing the possibility of disease spread,” according to a recent press release on the campaign.

Although this may be the largest vaccination effort that will use fractional dosing of the vaccine to date, it is not the first time that fractional dosing was used to quell a yellow fever outbreak. At IDWeek 2017, Daniel Lucey, MD, MPH, from the department of Medicine/Infectious Diseases at Georgetown University Medical Center discussed fractional dosing efforts made in Kinshasa, the capital of the Democratic Republic of the Congo. In July and August of 2016, health officials from different international organizations came together for the vaccination campaign in which they administered one-fifth of a regular dose of vaccine to upwards of 7 million individuals. These efforts succeeded in stopping an epidemic.

This same approach is being taken in Brazil’s vaccination strategy. According to the World Health Organization (WHO) and the Pan American Health Organization of the WHO, one-fifth of a regular dose still provides individuals with immunity against the virus for at least 1 year, and likely, even longer. Fractional doses of the yellow fever vaccine are not recommended long-term or as a replacement for routine immunization practices. Children between the ages of 9 months and 2 years as well as individuals with medical conditions will continue to receive the standard dose of the vaccine in Brazil’s campaign.

Supported by WHO and PAHO, Brazilian officials said their goal was to vaccinate about 22.3 million individuals—10.3 million from São Paulo and about 10 million from Rio de Janeiro. This week, the state of Bahia is expected to begin vaccination efforts that aim to inoculate about 3.3 million individuals as well.

According to a report from mainstream media source ABC News, however, the campaign, which started 3 weeks ago, has reached less than 20% of the targeted population—only 3.95 million individuals have been vaccinated so far.

At the same time, a yellow fever outbreak in Nigeria also has officials scrambling. As of the last Situation Report released by the Nigeria Centre for Disease Control (NCDC), confirmed cases have been reported in 7 states (Kwara, Kogi, Kano, Zamfara, Kebbi, Nasarawa, and Niger) as well as 12 Local Government Areas. As of January 2, 2018, there have been a total of 358 suspected yellow fever cases; out of 230 samples collected, 63 tested positive for the disease.

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