| Popis: |
• Numbers of paralytic and fatal cases of poliomyelitis reported in New York State since 1915 have been analyzed from the standpoint of cohort mortality, which follows the rate of a given group through successive time periods. The figures show that the mortality has decreased at least 75 % since the maximum in 1915, but that the reduction, which is ascribed to natural immunization and improved medical care, has affected only the children under 15 years of age. There has not been any comparable reduction in mortality for persons older than 15 years. The number of paralytic cases reported annually during the period 1942-1954 was strongly correlated with the number of deaths. |
