Circulating poliovirus derived from type 2 vaccine – Sudan

On August 9, 2020, the Federal Ministry of Health in Sudan notified the WHO of the detection of a circulating poliovirus type 2 (cVDPV2) vaccine in the country. According to the report, the virus is genetically related to Chad (sequencing results showed 12 to 19 nucleotide changes). Two cases of acute flaccid paralysis (AFP) have been reported. The first case, a 48-month-old child, began paralysis on March 7, 2020, and was from the city of Sulbi, Kas, South Darfur. The country is in the west of the country, bordering the Central African Republic, South Sudan and close to the border with Chad. The second case, a 36-month-old child, began paralysis on April 1, 2020, and was from the city of Shari, the town of AI Gedarif in the eastern state of Gedarif, near the border with Eritrea and Ethiopia. Both children received the last dose of bOPV (types 1 and 3) in 2019. The first study suggests that these cases are related to cVDPV2 from the occurrence of CHA-NDJ-1, which was first detected in October 2019 and is currently circulating in Chad and Cameroon, Eleven additional suspicious cases were also confirmed as cVDPV2 and field reports were consolidated. These cases are in the following countries – Red Sea, West Darfur, East Darfur, White Nile, Nile River and Gezira. Therefore, between 9 August and 26 August 2020, a total of 13 cVDPV2 cases were reported. In addition, three cVDPV2 positive environmental samples from Soba, Elgoz and Hawasha from Khartoum were detected (samples collected on March 29, 2020). The sequencing of viruses isolated in Sudan so far reflects that the viruses are related to viruses previously reported in neighboring Chad, from where there were several separate entries into Sudan from Chad. In Sudan, there is local circulation and continued sharing of transmission with Chad.

Public health response

Following the detection of cVDPV2 in the country, the following response activities are planned and / or implemented:

• The Acting Federal Minister of Health declared the government an epidemic of cVDPV2 in Sudan within eight hours on Zero Outbreak Day (August 9, 2020);
• The Ministry of Health, backed by a partner of the Global Initiative for the Eradication of Polio (GPEI), conducted a comprehensive field investigation and began implementing a Day Zero polio preparedness and response plan;
• A national outbreak response working group has been established with representatives of the WHO and UNICEF, the Federal Epidemiological Team has completed the terms of reference and composition of the National Technical Committee for Outbreak Control cVDPV2 and convened the first meeting on 9 August 2020;
• The Undersecretary of Health chairs the Steering Committee to respond to the outbreak, and the first meeting was convened on 9 August 2020;
• The Federal Epidemiological Team has advised state epidemiological administrators of South Darfur and Al Gedarif and other states with cases to activate the state emergency committee and begin implementing a polio preparedness and response plan;
• The response is coordinated with other departments such as health promotion and health emergencies; and cross-border coordination with neighboring countries is initiated.

WHO risk assessment

The WHO estimates that the risk of further international spread of cVDPV2 across Central Africa and the Horn of Africa will be high. With large population movements with other areas of Central Africa and the Horn of Africa. The polio program conducts a more thorough risk assessment for the entire region. Across the African continent, 172 type 2 cases were reported in 2020 in 14 countries.

WHO advice

It is important that all countries, especially those with frequent travel and contacts with countries and areas affected by polio, step up surveillance for acute flaccid acid paralysis to quickly detect any imports of the new virus and facilitate a rapid response. Countries, territories and areas should also maintain evenly high coverage by routine immunization at the county level to minimize the consequences of any introduction of a new virus.

The World Health Organization for Travel and Health recommends that all travelers to areas affected by polio be fully vaccinated against polio. Residents (and visitors longer than 4 weeks) from areas affected by polio should receive an additional dose of OPV or inactivated polio vaccine (IPV) within 4 weeks to 12 months of travel.

According to the advice of the Emergency Committee convened in accordance with International Health Regulations (2005), efforts to limit the international spread of poliovirus remain an emergency public health service of international importance (PHEIC). Countries affected by poliovirus transmission are subject to the Interim Recommendations. In order to comply with the Provisional Recommendations issued under the PHEIC, any country infected with poliovirus should declare an outbreak a national public health emergency and consider vaccinating all international travelers living or visiting the country for four or more weeks. Countries infected with cVDPV2 should encourage residents and long-term visitors to receive a dose of IPV four weeks to 12 months before international travel.

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