Key result
Mass OPV immunization campaign linked to ~67% drop in paralytic poliomyelitis cases in Shandong.
Why the study?
Widespread outbreaks of paralytic poliomyelitis occurred in Shandong province starting from 1988 despite emergency immunization efforts, necessitating new immunization strategies and surveillance systems.
Observational (n=863)
Absolute Event Rate: 95% vs 284%
Selective OPV campaigns failed to control outbreaks; leaves open whether mass campaigns are essential for effective control.
Widespread outbreaks of paralytic poliomyelitis occurred in Shandong province, China, starting from 1988. In 1989, 484 cases were recorded, which was the peak during the past 4 years. Although emergency immunization with trivalent oral poliovirus vaccine (OPV) was carried out in selected counties in 1989 and 1990, control of the outbreak was not satisfactory. OPV mass immunization campaigns were introduced to cover the whole province in early 1991, and the number of patients with paralytic poliomyelitis decreased to 95. In addition to this new immunization strategy, we began to construct new polio surveillance systems. These were a network for case-negative reporting and an immediate reporting system of acute flaccid paralysis (AFP). As for the case-negative reporting, presently more than 90% of counties have been reporting presence or absence of new AFP cases. Monitoring of AFP immediate reporting has also shown a gradual improvement in several aspects. These polio surveillance activities are crucial to polio eradication programme management.
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Chiba et al. (1992) conducted an observational in Paralytic poliomyelitis (n=863). OPV mass immunization campaign vs. Prior targeted emergency immunization was evaluated on Number of paralytic poliomyelitis cases. Following the introduction of province-wide OPV mass immunization campaigns in early 1991, the number of paralytic poliomyelitis cases in Shandong province decreased by about 60%, from 284 in 1990 to 95 in 1991.
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