What it took to draw a line under a polio outbreak in Sudan
The Republic of Sudan closed a polio outbreak on 15 September 2022. It had paralyzed 58 children across 42 districts before it stopped circulating.
This two-year old outbreak of circulating vaccine-derived poliovirus (cVDPV) type 2 began after the virus was imported from neighbouring Chad.
Click on the photo gallery to see what it took to close the outbreak.
Two technical assessment missions worked on scrutinizing available evidence and analyzing the absence of polioviruses across Sudan. The first mission, conducted virtually in October 2021, shared their recommendations with Sudan’s polio eradication team to ramp up their efforts across the country.
A second official outbreak response assessment team undertook the next phase of this detailed task. They visited Khartoum and six of Sudan’s 18 states as part of their work from 24 July to 1 August 2022.
Both review teams comprised experts from the World Health Organization (WHO) and the United Nations Children’s Fund (UNICEF). Their skills and experience ranged from global public health, epidemiology and biostatistics to surveillance, vaccine management and communication.
They worked hand in hand with the Federal Ministry of Health of Sudan, with state-level ministry staff and with health workers at ground level.
After a close review of the functionality and sensitivity of the country’s surveillance system, the assessment team noted that Sudan’s acute flaccid paralysis (AFP) surveillance indicators are indeed meeting the necessary standards. The gold standard for polio surveillance is through searching for AFP in children, and testing stool samples to confirm the presence of the virus.
All poliovirus samples collected since 18 December 2020, the date of onset of paralysis of the last child affected in the outbreak, were processed like clockwork in Sudan’s laboratory. They were reported as poliovirus negative and recorded.
The missions noted Sudan’s 14 environmental surveillance sites are also collecting and testing waste water samples regularly, in line with international protocol.
During the polio outbreak, 14 sewage samples in the country’s bustling capital, Khartoum, tested positive for cVDPV2, indicating circulation there.
As part of their work, the technical mission also reviewed the core functions of Sudan’s laboratories and the country’s preparation mechanisms for poliovirus events or outbreaks. This also included data on population immunity, childhood immunization and vaccine management protocol.
A large part of Sudan’s success can be attributed to its swift response to the outbreak as soon as it was confirmed.
The country conducted two high-quality nationwide campaigns in all 18 states to curb virus spread in November 2020 and January 2021. Each campaign delivered monovalent oral polio vaccine type 2 (mOPV2) to over 8 million under-fives.
Weighing in on this milestone, senior experts in WHO’s polio eradication programme, including
Dr Hamid Jafari, WHO Director for Polio Eradication in the Eastern Mediterranean Region, and Dr Ni’ma Saeed Abid, WHO Representative to Sudan, lauded public health officials and immunization health workers on the ground for their swift response to the outbreak.
They reiterated the importance of maintaining sensitive AFP surveillance, ensuring better outbreak preparedness and response, enhancing coverage of essential immunization, and strengthening cross-border coordination. This is crucial given Sudan remains at high risk of importation of polioviruses.
Following this extensive work, the outbreak response assessment team concluded that the spread of cVDPV2 has indeed stopped, and that the outbreak is over.
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