The epidemiological and etiological aspects of poliomyelitis and acute flaccid paralysis (AFP) in Russia and Vietnam were analysed and compared. The polio-free status is maintained on 14 territories of Russia and 29 provinces of South Vietnam. The quality of epidemiological and virological surveillance for acute flaccid paralysis is in accordance with the requirements of the national and international polio surveillance systems. All AFP cases were revealed, registered, reported and investigated in both countries. The percentage of poliovirus isolation from 2492 samples collected from patients with acute flaccid paralysis and contact persons in different years in Russia ranged from 1.3 & PLUSMN;0.89 to 9.8 & PLUSMN;0.79. In South Vietnam, 2143 samples from patients with acute flaccid paralysis were investigated. In Russia and Vietnam, we isolated vaccine polioviruses of all three types with predominance of type 3 polioviruses (63% and 50%, respectively) in both countri es. From AFP patients in Russia and Vietnam, polioviruses were isolated in 4.9% and 1.0% studied samples, respectively. Some VDPV strains were revealed on the territories of Russia and South Vietnam. Here, we describe five cases of vaccine-associated paralytic poliomyelitis registered in Russia and two cases of AFP caused by VDPV type 2 reported in Vietnam. To prevent the risk of developing vaccine-associated paralytic poliomyelitis, it is indispensable to ensure high-quality surveillance for acute flaccid paralysis, maintain 95% polio vaccine pediatric coverage and strictly comply with sanitary legislation, including the National Vaccination Schedule when vaccinating children, to improve virological surveillance of polioviruses using classical and new virological and molecular methods and to continue research on poliomyelitis, including development of new safe and effective poliovirus vaccines able to induce both humoral and mucosal immuni ty. The systematic control of adequate polio vaccination is indispensable in order to prevent transmission of imported wild polioviruses into polio free countries as well as circulation of vaccinederived polioviruses worldwide.
