WHO: Fractional dosing a potential option for yellow fever vaccine shortages

The World Health Organization (WHO) Strategic Advisory Group of Experts (SAGE) on Immunization presented evidence on Friday that yellow fever vaccine given at one-fifth of the regular dose could be used to control an outbreak in case of vaccine shortages.

The reduced dose, known as fractional dosing, is currently under consideration as a short-term measure and could be used in emergencies. Fractional dosing, however, is not recommended for routine immunization because there isn’t enough data to support the practice for regular use.

Experts agreed with the proposal at a WHO meeting to consider potential shortages in yellow fever vaccines due to an outbreak in Angola or the Democratic Republic of the Congo.

“Yellow fever outbreaks in Angola, Democratic Republic of the Congo and Uganda are placing unprecedented demands on vaccine supply for emergency vaccination campaigns to control the spread of the disease,” Jon Abramson, chair of SAGE, said. “Right now we have enough vaccines in the global stockpile to cope with the ongoing outbreaks if there are no further extensions. However, given the wide spread of the disease in Angola and the potential for it to get out of control in the city of Kinshasa, in the Democratic Republic of the Congo, WHO and partners are seriously considering the use of this dose-sparing strategy to prevent transmission through large-scale vaccination campaigns.”

WHO’s response strategy for outbreaks concentrates on five specific areas to reduce potential outbreaks, including surveillance and risk assessment, vaccination, case management, social mobilization and risk communication, and vector control.