Immunity status against poliomyelitis in persons 13-14 years old living in Rome

The immunity against poliomyelitis in 1000 subjects 13-14 years old was evaluated. Neutralizing antibodies against poliovirus type 1, 2 and 3 were detected in 97.6%, 95.8% and 70% of samples, respectively. 3/1000 (0.3%) subjects were simultaneously seronegative to the three types. WHO does not suggest a protective level of International Units (IU), but our data indicate that such level is 0.45 IU for polio type 1, 0.65 IU for the type 2 and 0.138 for the type 3. A booster dose of vaccine in adolescence to ensure personal and herd immunity is recommended. (C) 1997 Elsevier Science Ltd.