| artificial herd immunity to poliomyelitis in a semirural community in south africa. | the sera of 139 children aged between 8 months and 6 years from the town of port alfred in the eastern cape province were examined for antibodies to the three types of poliovirus. a protective level of antibody to type 1 virus was found in 73.4% of the sera. the figures for types 2 and 3 were 94.2% and 68.3% respectively. the results indicate good herd immunity to poliomyelitis. no cases of paralysis or isolations of poliovirus had been reported from the area for the 6 years preceding the survey ... | 1981 | 6272430 |