Epidemiology of poliomyelitis in a slum of Bombay.

A disease prevalence and immunization coverage survey in a typical slum in Bombay in the year 1988 revealed 93 children with residual poliomyelitis amongst 14,439 children below 9 years of age, indicating high (33.0/100,000 population) annual incidence of poliomyelitis. Only 62 (66.6%) of these 93 lame children sought admission in hospital during the acute phase of illness. The high incidence was attributed to a low immunization (OPV) coverage level in the most vulnerable age group. The immunization coverage for 3 doses of oral polio vaccine below 2 years of age was 43.5%. A large number of children were not commencing their immunization schedule at the right age. The survey indicated a poor "community participation" in the immunization programmes due to a poor "health awareness".

Poliomyelitis surveillance and vaccine efficacy in Bombay, 1982-87.

Reported are updated data on poliomyelitis surveillance in Bombay for the period 1982-87 and estimates of the efficacy of oral poliovaccine (OPV) calculated by the case exposure method, using two approaches. The first, a screening technique that used only data on the reported number of doses of vaccine administered and the immunization status of all poliomyelitis cases, appeared to underestimate the true vaccine efficacy. In the more rigorous second technique, which used data for children of the same age group, geographical areas, and study year, obtained from immunization coverage surveys, and information on the immunization status of poliomyelitis cases, the results indicate that the OPV vaccine efficacy for fully immunized children aged 12-23 months exceeded 90%. These findings show that the estimated efficacy of OPV is high in Bombay and that, in general, vaccine efficacy should be re-estimated using more rigorous techniques if preliminary screening estimates indicate a lower than expected efficacy. In Bombay, poliomyelitis therefore results primarily from a failure to fully vaccinate all eligible children rather than as a result of vaccine failure. Furthermore, the age distribution of cases suggests that the strategy of focusing immunization activities on children aged under 1 year is epidemiologically correct.

Poliomyelitis surveillance and vaccine efficacy in Bombay, 1982-87

Reported are updated data on poliomyelitis surveillance in Bombay for the period 1982-87 and estimates of the efficacy of oral poliovaccine (OPV) calculated by the case exposure method, using two approaches. The first, a screening technique that used only data on the reported number of doses of vaccine administered and the immunization status of all poliomyelitis cases, appeared to underestimate the true vaccine efficacy. In the more rigorous second technique, which used data for children of the same age group, geographical areas, and study year, obtained from immunization coverage surveys, and information on the immunization status of poliomyelitis cases, the results indicate that the OPV vaccine efficacy for fully immunized children aged 12-23 months exceeded 90 percent

These findings show that the estimated efficacy of OPV is high in Bombay and that, in general, vaccine efficacy should be re-estimated using more rigorous techniques if preliminary secreening estimates indicate a lower than expected efficacy. In Bombay, poliomyelitis therefore results primarily from a failure to fully vaccinate all eligible children rather than as a result of vaccine failure. Furthermore, the age distribution of cases suggests that the strategy of focusing immunization activities on children aged under 1 year is epidemiologically correct(AU)

Persistence of rabies antibody 5 years after pre-exposure prophylaxis with human diploid cell antirabies vaccine and antibody response to a single booster dose.

In 1978, 22 staff members of the National Institute of Virology, Pune, India, were given two doses of human diploid cell antirabies vaccine (HDCV) for primary pre-exposure prophylactic immunization; the interval between the two doses being approximately 4 weeks. Eighteen of these 22 vaccinees were given a booster dose 1 year later. All 18 vaccinees developed protective levels of antibody; most of them had antibody levels exceeding 10 IU/ml. In 1984, 5 years after the booster dose, 11 (79.0%) of 14 vaccinees tested still possessed neutralizing antibody levels ranging from 0.5 IU/ml to 10 IU/ml. Fourteen days after the administration of a booster dose, the antibody levels ranged from 10 to greater than or equal to 100 IU/ml for all except one vaccine (5.2 IU/ml). These findings demonstrate that the majority of vaccines retained detectable neutralizing antibody after pre-exposure prophylaxis for as long as 5 years and that a single booster dose thereafter evoked a good antibody response.

Neutralizing antibody response to Japanese encephalitis inactivated mouse brain vaccine among laboratory personnel.

Among vaccinees given two doses of JE Nakayama strain liquid vaccine, 41.8% had significant neutralizing (N) antibody response to the P20778 strain and 48.6% to the Japanese Nakayama strain. Among vaccinees who received three doses of the freeze-dried vaccine, the proportion of positive reactors was 53.8% when the sera were tested with the P20778 strain and 47.4% with the Nakayama strain. A fairly large proportion of those vaccinees who had responded positively to the latter vaccine were found to have lost detectable N antibodies to the P20778 strain and a smaller proportion to the Nakayama strain 13 to 17 months after the third dose of vaccine. Following the administration of a booster dose of the vaccine after this time interval, 65.2% and 56.5% of vaccinees responded positively to the P20778 strain and the Nakayama strain, respectively. The differences between the proportion of positive reactors to the two strains were not significant either for the liquid vaccine or the freeze-dried vaccine. An important finding was the priming effect of infection with West Nile (WN) virus before vaccination. Those vaccinees who had N antibody to WN virus before vaccination had a significantly higher N antibody response to the P20778 strain of JE virus than those who had no detectable antibody to WN virus. These findings indicate that the JE Nakayama strain vaccine would be efficacious in India, particularly in view of the widespread prevalence of WN virus infection.