Poliomyelitis in vaccinated children.

Fifty-two children who had received at least 3 properly spaced doses of oral polio-vaccine and had developed acute poliomyelitis inspite of vaccination were studied clinically and serologically. This group (A) was compared with 28 children with poliomyelitis who had not received any vaccination (Group B). A much higher incidence of provocative injection and a better muscle power on presentation was seen in Group A as compared to Group B. Polio-virus type 2 was the commonest etiological agent in Group A (42.3%) whereas type I virus was most commonly seen in Group B (78.6%). A total 53.8% of cases of Group A had protective antibody titres to at least one poliovirus type in the acute phase sera, compared to only 4% from Group B. Six per cent from Group A had protective antibodies to all three virus types, disease in these cases was caused by non-polio agents. Two cases in Group A were possibly vaccine induced paralysis. Recovery, after 60 days, was much better in Group A as compared to Group B. Mortality in the two groups was comparable.