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Optimizing oral polio vaccine delivery

This area of research focuses on identifying ways of reaching more children and increasing immunization coverage during supplementary immunization activities.

Delivering vaccines in hard-to-reach communities: the SIAD approach

The SIAD – Short Interval Additional Dose – approach involves administering two doses of monovalent oral polio vaccine (mOPV) over the course of one or two weeks. Historically, trivalent OPV had to be given over an interval of four to six weeks. This more rapid approach to delivering vaccines is particularly valuable in areas where children are difficult to reach (e.g. conflict areas, nomadic populations), and may play an important role in stopping new outbreaks.

While the programmatic imperative for using mOPVs during SIAD campaigns is persuasive, the scientific basis for SIAD is not fully established. To correct this gap, a clinical trial will be carried out in Pakistan in 2012, to assess SIAD rounds in young infants.

Short Interval Additional Dose (SIAD) trial - Pakistan

Assessing immunization coverage - LQAS

Studies have shown that the Lot Quality Assurance Sampling (LQAS) method is a feasible and useful way to monitor and guide vaccination campaigns. LQAS is now widely used to monitor polio vaccination campaigns, and is an important component of the Global Polio Emergency Action Plan 2012-2013 (to be published in May 2012).


Conducting LQAS surveys is straightforward, making it a very operational tool to detect pockets of low vaccine coverage. The LQAS method involves dividing the population into “lots” and randomly selecting individuals in each lot. If the number of unvaccinated individuals in the sample exceeds a pre-set decision value, then the lot is classified as having an unsatisfactory level of vaccine coverage and mop-up activities are recommended.


The Global Polio Eradication Initiative (GPEI), together with regional counterparts and external experts, have reviewed and updated the manual of methodology and interpretation of LQAS, for post-vaccination campaign quality assessment. The signficant changes compared to previously available manuals include the new interpretation framework, which has three categories of SIA quality:


  • A clear "pass" (consisting of 90% "accepted lots")
  • An "intermediate" (of 80-89% "accepted lots")
  • A "do not pass" (anything below 80% "accepted lots")

Additionally, the new manual recommends the collection of vaccination campaign awareness information.


The new manual will be a working document, periodically revised as additional feedback on methodologies is received to ensure LQAS can be the most practical and relevant tool, as possible,  to support the global polio eradication effort.


Manual of methodology and interpretation of LQAS

Use of Information Technology and Geographic Information Systems (GIS)

Everyday technology continues to be assessed to help improve the quality of polio SIAs. Near real-time data collection and analysis is being conducted by independent monitors through mobile phones and EpiSurveyor software to help monitor the quality of SIAs. Evaluated during SIAs in Kenya and Pakistan, this technology could further enhance the scaled-up independent monitoring and LQAS efforts.

In Nigeria in November 2010, a pilot study was carried out to determine the feasibility of using Geographic Information Systems (GIS) to support both implementation and monitoring of SIAs. GIS - a tool used to capture, store, analyse and present data linked to location - helped track and map the movements of vaccination teams in relation to prepared microplans.

Further assessments of these and other metholodigies continue to be expanded.

Improving communication

Research suggests that there are still gaps in knowledge, attitudes and perception among caregivers and vaccinators in many countries. These gaps can be a barrier to achieving high vaccine coverage. More studies are needed to test different communication and social mobilization strategies and evaluate their impact on vaccine acceptance and coverage.