Circulating vaccine-derived poliovirus type 2 – Democratic Republic of the Congo
In the Democratic Republic of the Congo (DRC), two separate circulating vaccine-derived poliovirus type 2s (cVDPV2s) have been confirmed. The first cVDPV2 strain has been isolated from two acute flaccid paralysis (AFP) cases from two districts in Haut-Lomami province, with onset of paralysis on 20 February and 8 March 2017. The second cVDPV2 strain has been isolated from Maniema province, from two AFP cases (with onset of paralysis on 18 April and 8 May 2017) and a healthy contact in the community.
Public health response
The Ministry of Health, supported by WHO and partners of the Global Polio Eradication Initiative (GPEI), has completed a risk assessment, including evaluating population immunity and the risk of further spread.
Outbreak response plans are currently being finalized, consisting of strengthening surveillance, including active case searching for additional cases of AFP, and supplementary immunization activities (SIAs) with monovalent oral polio vaccine type 2 (mOPV2), in line with internationally-agreed outbreak response protocols.
Surveillance and immunization activities are being strengthened in neighbouring countries.
WHO risk assessment
WHO assesses the risk of further national spread of these strains to be high, and the risk of international spread to be medium.
The detection of cVDPV2s underscores the importance of maintaining high routine vaccination coverage everywhere, to minimize the risk and consequences of any poliovirus circulation. These events also underscore the risk posed by any low-level transmission of the virus. A robust outbreak response as initiated is needed to rapidly stop circulation and ensure sufficient vaccination coverage in the affected areas to prevent similar outbreaks in the future. WHO will continue to evaluate the epidemiological situation and outbreak response measures being implemented.
It is important that all countries, in particular those with frequent travel and contacts with polio-affected countries and areas, strengthen surveillance for AFP cases in order to rapidly detect any new virus importation and to facilitate a rapid response. Countries, territories and areas should also maintain uniformly high routine immunization coverage at the district level to minimize the consequences of any new virus introduction.
WHO’s International Travel and Health recommends that all travellers to polio-affected areas be fully vaccinated against polio. Residents (and visitors for more than four weeks) from infected areas should receive an additional dose of OPV or inactivated polio vaccine (IPV) within four weeks to 12 months of travel. As per the advice of the Emergency Committee convened under the International Health Regulations (2005), efforts to limit the international spread of poliovirus remains a Public Health Emergency of International Concern (PHEIC). Countries affected by poliovirus transmission are subject to Temporary Recommendations. To comply with the Temporary Recommendations issued under the PHEIC, any country infected by poliovirus should declare the outbreak as a national public health emergency and consider vaccination of all international travellers.