Persistence of vaccine-derived poliovirus following a mass vaccination campaign in Cuba: implications for stopping polio vaccination after global eradication

Background With substantial progress made toward polio eradication, develop ing the appropriate strategy for discontinuing global oral poliovirus vacci ne (OPV) after global eradication becomes increasingly important. At issue is the theoretical risk of independent circulation of potentially virulent OPV-derived strains. Because Cuba uses OPV only in mass campaigns, it repre sents an ideal site to assess vaccine-derived poliovirus persistence. Methods Infants born after the 1997 biannual mass campaigns were evaluated for past (neutralizing antibody) or current (virus excretion) evidence of v accine-derived poliovirus exposure. We obtained sera and/or stool specimens from 861 infants; a second serum from 218 infants. Results All stool specimens were poliovirus negative. Of 762 infants, 113 ( 14.8%) had initially detectable poliovirus type I antibody, 193 (25.3%) typ e 2, and 94 (12.3%) type 3. A precipitous antibody decline occurred in init ially positive sera. Conclusions Our results suggest that in a country with high population immu nity, vaccine-derived virus is unlikely to establish ongoing circulation.