Lower Doses of Yellow Fever Vaccine Could be Used in Emergencies- WHO

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In short
This approach, known as fractional dosing, is under consideration as a short-term measure, in the context of a potential vaccine shortage for use in emergencies. This approach is not proposed for routine immunization, as there is not yet enough data available to show that lower doses would confer the life-long protection provided by a vaccination with one full dose.

The yellow fever vaccine given as one fifth of the regular dose could be used to control an outbreak in case of vaccine shortages, Health Experts have recommended.

Experts agreed with this proposal at a meeting convened by the World Health Organisation to consider potential shortages in yellow fever vaccine due to the outbreak in Angola, Democratic Republic of Congo and parts of Uganda.

WHO Strategic Advisory Group of Experts (SAGE) on Immunization reviewed existing evidence that demonstrates that using a fifth of a standard vaccine dose would still provide protection against the disease for at least 12 months and possibly much longer.

This approach, known as fractional dosing, is under consideration as a short-term measure, in the context of a potential vaccine shortage for use in emergencies. This approach is not proposed for routine immunization, as there is not yet enough data available to show that lower doses would confer the life-long protection provided by a vaccination with one full dose.

"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 the WHO Strategic Advisory Group of Experts (SAGE) on Immunization says.

"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."

At the request of the Emergency Committee regarding yellow fever convened by WHO's Director-General on 19 May, the WHO secretariat has been exploring options, based on existing evidence, on ways to increase vaccine supply in case of urgent need.

SAGE was asked to review the evidence and options presented by WHO. A formal evaluation and recommendations by SAGE on the use of lower doses of yellow fever vaccine are planned for October 2016.

In the interim, SAGE found that the available evidence is sufficient to determine that fractional dosing of yellow fever vaccine to one fifth of the standard dose (0.1ml instead of 0.5ml) could be a safe and effective option for mass vaccination campaigns to control urban outbreaks in situations of acute vaccine shortage.

More research is needed to find out whether fractional doses would be effective in young children, who may have a weaker immune response to yellow fever vaccine.

Yellow fever is the only disease specified in the International Health Regulations (IHR) for which countries may require proof of vaccination from travelers as a condition of entry. However, a  yellow fever vaccine given at a fractional dose would not qualify for a yellow fever certificate.

 

About the author

Sylvia Nankya
Sylvia is an Editor and Media Trainer with Uganda Radio Network. She has been a URN staff member since 2013. Sylvia has previously worked as a reporter and news anchor with Radio One (2001-2009) and with Vision Group (2009-2011). Six of her active years in Journalism were spent covering the Parliament of Uganda.

Over the past few years, Sylvia has worked to promote the positive development of societies recovering from conflict through training journalists on choices of stories, how they report issues and use of appropriate language in covering conflict and post-conflict situations.

She is an Alumni of RNTC- Holland, Les Aspin Centre for Government at Marquette University-WI, USA and a Community Solutions Fellow.