The coverage of children by immunization against diphtheria, pertussis and tetanus during the first 3 years of life as indicated in forms No. 112 and No. 63 in 4 districts of Moscow was studied on the basis of the analysis of 1688 children's development histories. The coverage of children by immunization was found to be on the average 71.7%, fluctuating in individual districts from 58.6% to 85.9%. Immunization against measles covered 41.8% of children with fluctuations 24.2-51.2%. The most frequent reasons for the absence of prophylactic immunization in children during the first 3 years of life, or belated immunization in comparison with the specified terms, were contraindications due to neurological diseases (40.4%), exudative diathesis (15.9%) and recurrent viral infections (16.2%). Medical objections to immunization without sufficient grounds constituted 12.1% of all contraindications; among such objections those given by neuropathologists (9.8%) and pediatricians (2.3%) prevailed. To increase the coverage of children by immunization in the specified terms, the use of such measures as improving work with parents (explaining to them the importance of timely prophylactic immunization) and strict observance of instructions on medical contraindications may be considered most effective.
Analysis of observations carried out under practical conditions (165 patients with pertussis from 48 foci) and the results of controlled epidemiological trial on the discontinuance of compulsory isolation of pertussis patients at schools (12 classes, 402 children) showed that isolation of the patients failed to stop the spread of infection in the focus. This was attributed to incomplete detection of the patients and their late isolation in conditions of wide incidence of mild forms and formes frustes of pertussis. When patients suffering from pertussis were left at school, there occurred no increase in the spread of the infection in the focus, in duration or severity of the disease and no increase of the period of discharge of the causative agent. However, the number of days of the patient's absence from school was greatly reduced. Taking into consideration the absence of an attack-like cough in patients with formes frustes, short duration and preponderance of the attacks at night in patients with a mild form of pertussis, no disturbances in the general condition of the child, and also no indications to the treatment, schoolchildren should be isolated by clinical indications only (pyrexia, marked catarrhal phenomena, frequent attack-like cough, complications, concomitant diseases); they can be admitted to school as soon as the mentioned signs subsided irrespective of the time lapse from the onset of the disease.
On the basis of analysis of whooping cough incidence in 1959 to 1975 in Moscow the authors present characteristics of the epidemic process under conditions of planned many-year immunization of children against this infection. Whooping cough morbidity proved to undergo significant changes-from sharp falls the first 8 years of immunization to a relative stabilization with a gradual reduction the last 5 years. Marked seasonal and periodic elevations persist against the background of reduction of morbidity. Preschool- and schoolchildren are equally involved in the epidemic process; the most frequently involved are nonvaccinated children aged 1 year and 4 to 10 years, which lost postvaccinal immunity. Further reduction of the severity of whooping cough and increase in the number of unimanifested forms of the infection was noted. This was apparently connected not only with immunization, but also with the reduction of the virulence of H. pertusis detected in studying the cultures isolated in Moscow from 1967 to 1974. The intensity indices of the epidemic process in whooping cough pointed to the necessity of using a more effective vaccine for the protection of children from whooping cough, despite the noted reduction of morbidity, and diminished severity of the course of the disease, and of the causative agent virulence.
The analysis of pertussis morbidity and the state of immunity to pertussis has made it possible to evaluate the existing epidemiological situation as unfavorable. The restraining influence of specific prophylaxis on the epidemic process of pertussis becomes weaker due to the growing number of nonimmunized children; for this reason, the maximum morbidity rate in pertussis is observed among children under 5 years of age, as it was at the period before the introduction of mass immunization against pertussis. To prevent further possible increase in the intensity of the epidemic process of pertussis and in the severity of the clinical course of the disease, the number of children under 3 years of age, not immunized against pertussis, must be reduced by limiting the number of children exempted from immunization on medical grounds and by increasing the proportion of children immunized from the age of 3 months.