The ten-years experience of acute flaccid paralysis (AFP) surveillance in Belarus has been summarized. Among 456 AFP cases reported from 1996 to 2005, 11 were classified as vaccine-associated paralytic poliomyelitis (VAPP), 445--as non-polio AFP. The risk of VAPP for the period 1996-2001 was 1 case per 745,000 used doses of oral poliovaccine (OPV). For the recipients of OPV the risk was 1 case per 911,700 doses and for the first-dose recipients--1 case per 96,000 doses. The high incidence of VAPP was a reason for implementation of sequential polio vaccination schedule in 2000. Guillain-Barre syndrome dominated among non-polio AFP (39.3% of cases); more rare were traumatic neuritis (27.9% of cases), transient monoparalysis (12.1%), myelitis (7.6%). Non-polio AFP differed from VAPP by following epidemiological and virological characteristics: predominance of previously repeatedly vaccinated against poliomyelitis; development of paralysis in long-term period after vaccination; isolation of non-polio viruses belonged to three serotypes of Coxsackie B viruses (B1, B4, B6) and six serotypes of Echo viruses (6, 7, 11, 14, 24, 25) in 8.1% of cases; absence of typical for polio residual paralyses in patients who excreted vaccine polioviruses.

The frequency of vaccine poliovirus isolation from children aged under 3 years was studied in Belarus, a country with a high level of immunization against poliomyelitis. Antigenic and genetic characteristics of the isolated strains were studied. Vaccine poliovirus detection rate was high (11.8%). Polioviruses were isolated from children immunized recently (27.2%), immunized more than 2 months before (7.5%), and from non-immunized children (9.8%). An appreciable number (36.1%) of the isolated strains were antigenically and/or genetically modified derivatives of Sabin virus. Epidemiological data and genetic characteristics of the isolated polioviruses indicate that some of them can be sufficiently transmissive for maintaining their "silent" circulation even in a population with a high level of immunization.

In 1996 the immunization of children against measles, mumps and rubella with combined vaccine Trimovax ("Pasteur Mérieux Connaught", France) was carried out in the Republic of Belarus. The reactogenicity of the vaccine was studied in 372 children. To evaluate immunological effectiveness, the sera of 324 children were used. Postvaccinal reactions of different intensity were registered in 5.6% of the children; of these, 1.3% exhibited severe reactions. Among the vaccinees, protective titers of antibodies to measles were found in 97.6% to mumps, in 93.8% and to rubella, in 96.0% of the children. Antibodies to all three components of the vaccine were present mainly in high and moderate titers. The results thus obtained indicate that, Trimovax was well tolerated and proved to be immunologically active.