OUTBREAK OF VACCINE DERIVED POLIOVIRUS IN NIGERIA

UNCLAS SECTION 01 OF 02 ABUJA 002237 SIPDIS SIPDIS CDC ALSO FOR DIRECTORS EMERGENCY OPERATION CENTER E.O. 12958: N/A TAGS: TBIO EAID DEOC SOCI PGOV NI SUBJECT: OUTBREAK OF VACCINE DERIVED POLIOVIRUS IN NIGERIA ¶1. Summary. An outbreak of at least 69 circulating Vaccine Derived Polio Virus (cVDPV) cases have been reported between 2006-7 mostly in Nigeria's northern states of Kano, Kaduna, Katsina, Bauchi, and Jigawa due to low immunization of children under five years. Internationally, cVDPVs has been known to appear in areas with low polio vaccination coverage. Immunization activities have subsequently been increased in these states which have limited the number of cVDPVs cases and their spread. Wild Polio Virus (WPV) remains a greater threat to children in Nigeria than cVDPVs. Achieving high polio immunization coverage is the only way to prevent further cVDPV outbreaks. End Summary. Nigeria's Outbreak -------------- ¶2. cVDPV is a rare, mutated, but weakened form of poliovirus that is transmitted from immunized to un-immunized or poorly immunized children that causes paralysis. This transmission occurs when un-immunized or under-immunized children come in contact with the faeces excreted from vaccinated children or a faecally contaminated source which contains the mutated form of poliovirus. These cases are generally found in environments with poor hygiene, sanitation and low immunization coverage. ¶3. In 2006, the Global Polio Laboratory Network (CDC/Atlanta) alerted the WHO and the Nigerian National Program on Immunization about the circulation of VDPV in several states in Northern Nigeria. As of August 17, 2007 there are an estimated 69 cases of cVDPVs. The cVDPVs detected in Nigeria are of the Type 2 polio virus. Most of the cases have been reported from the northern states of Kano, Kaduna, Katsina, Bauchi, and Jigawa - states that have also reported significant numbers of wild poliovirus cases. ¶4. The same areas that are affected by Wild Polio Virus (WPV) transmission are also affected by cVDPVs. This is due to the low polio immunization status of children under five years. Although more and more children are being reached with polio immunization, up to 30% of children under five years are still not immunized in some areas, leading to low population immunity against polio. The factors that contribute to this very low population immunity are: (a) low routine immunization coverage, (b) sub-optimal quality of Immunization Plus Days (IPDs or "polio rounds") with significant �0A;numbers of children missed and remaining unvaccinated after the rounds, and (c) the limited use of trivalent Oral Polio Vaccine (tOPV),which prevents the occurrence of all three types of polio virus (Types 1, 2 and 3). Monovalent OPV1 and monovalent OPV3 are being used due to their effectiveness against Type 1 and Type 3 poliovirus, which are the viruses seen in Nigeria. ¶5. From January 2006 to July 2007 an estimated 230 million doses of OPV have been administered to children under five years in Nigeria. The total number of reported WPV cases for that same period is 1,325. However, the number of cVDPV cases reported as of August 17, 2007 is 69. This clearly demonstrates that WPV remains both more prevalent and a far greater threat to children in Nigeria than cVDPVs. Moreover, there is some belief that reported WPV cases may in fact be under-estimated. The Response -------------- ¶6. In response to the preliminary information on possible circulation of VDPVs in 2006, efforts were undertaken to improve population immunity in all the affected states, as well as other high risk states in Northern Nigeria. In line with the Global Polio Eradication Initiative (GPEI) recommendation, polio campaigns using trivalent OPV that provides immunity against all three strains of wild polio virus were conducted in Nigeria (November 2006, January 2007, March 2007 and September 2007). Since the Nigerian cVDPV is a similar, but actually weaker form of the Type 2 WPV, the trivalent vaccine remains very effective in limiting the incidence of cVDPVs. These rounds of immunization have limited the number of cases of cVDPVs and their geographical spread and have also reduced the incidence of wild polio virus cases in Northern Nigeria. However the use of the trivalent vaccine for this purpose has not eliminated the need for Nigeria to continue with focused monovalent rounds. ¶7. Information on the Nigerian cases was made public on September 21, 2007 in CDC's Mortality and Morbidity Review (MMWR) and in the WHO Weekly Epidemiological Record (WER). Since then and with support from development partners, the government of Nigeria (GON) has initiated dialogue with religious and traditional leaders. Detailed plans with media strategies for reassuring state and district leadership, general public, and technical experts have also been developed. However, the public response from the GON has been very slow despite increasing pressure from development partners. ABUJA 00002237 002 OF 002 Global situation -------------- ¶8. It should be noted that cVDPV cases have been recorded in other countries where immunization coverage was low, such as Egypt, Indonesia, Cambodia, China, and Myanmar. These situations were brought under control by increasing immunization coverage with the use of trivalent OPV. Less than 200 cVDPV cases have been reported over the past 10 years, while over 10 billion doses of polio vaccine have been administered to more than 2 billion children. During the same period, more than 33,000 children were paralyzed by wild poliovirus, while more than 6.5 million polio cases were prevented by the polio vaccine. ¶9. Comment. Wild polio virus remains a greater threat to children in Nigeria than circulating vaccine derived polio virus. Achieving high immunization coverage is the only way to prevent further cVDPV outbreaks. The GON needs to act quickly on this issue to sustain the gains made in polio eradication and to prevent a potential backlash. Post has also recommended to key Ministry of Health counterparts the need for clear and consistent public education to allay fears, increase understanding and acceptance of GON immunization strategies, and to significantly improve immunization coverage. End Comment. PIASCIK