Duration of effectiveness of pertussis vaccine: evidence from a 10 year community study

A 10 year study of whooping cough in a discrete general practice community was performed to assess longitudinally the efficacy of pertussis vaccine from one to seven years after immunisation. Of the 436 cases of whooping cough over 10 years, 326 occurred in children aged 1-7 years. The rate of immunisation was known for each cohort of children born during each year, and the attack rate of whooping cough was thus calculated for those immunised and unimmunised. The attack rates were highest in those cohorts exposed to the epidemics of 1977-9, 1981-3, and 1985-7. The efficacy of the vaccine was calculated as a percentage as (attack rate in unimmunised group—attack rate in immunised group) × 100/attack rate in unimmunised group. It fell from 100% in the first year to 46% in the seventh, being 84% in the fourth and only 52% in the fifth.Thus the pertussis vaccine or its schedule of use does not seem to provide sufficient herd immunity to prevent outbreaks of whooping cough. Matters might be improved if vaccination against pertussis were included in the preschool immunisation programme.     

Attack rates of notified whooping cough in immunised and unimmunised children.

The incidence of whooping cough among immunised children under the age of six and among children of the same age who were not fully immunised was ascertained by analysing whooping-cough notifications from several health authorities. In the first three years of the study the results showed that attack rates were much higher in children who were not fully immunised than in those who were. This finding suggests that current vaccines provide young children with substantial protection against whooping cough.     

Whooping cough after stopping pertussis immunisation.

An epidemic of whooping cough occurred in a rural practice in Shetland, containing 144 children under 16. Before July 1974 all children were immunised against pertussis, but after that date immunisation was stopped. Of the 134 children studied, 93 had been immunised. Sixty-five of the children developed whooping cough. The incidence of infection was similar in those who had and had not been immunised. The incidence was also similar in those born before and after July 1974. There was no evidence to support the routine use of pertussis immunisation in rural Shetland.     

Study of intellectual performance of children in ordinary schools after certain serious complications of whooping cough. Swansea Research Unit of the Royal College of General Practitioners.

In a case-control study 27 index children from ordinary schools who had had convulsions or apnoea as a complication of whooping cough about eight years previously were compared with 27 children who had never had whooping cough and 15 who had had whooping cough without complications. Other factors likely to cause intellectual impairment after conception were considered. The index group had a significantly lower median intelligence quotient and poorer school attainment than either of the control groups. The results support the hypothesis that convulsions or apnoea as a complication of whooping cough may be associated with subsequent intellectual impairment.     

Impact of whooping cough on patients and their families.

The effects of whooping cough were studied in 21 children admitted to hospital with the disease and in their families. The illness caused considerable distress to both child and family. Parents suffered especially from fears for the life and health of their child and from serious loss of sleep. Two months after admission the child''s behaviour was still disturbed, but in most cases the rest of the family had returned to normal. There was much misunderstanding and misinformation about whooping cough among both parents and doctors.     

Effect of vaccination on severity and dissemination of whooping cough.

A study was undertaken in general practice to clarify those factors, especially vaccinations, that influence the clinical picture and infectivity of whooping cough in the community. Although the range of the disease encountered was fairly mild, its duration was notable (mean +/- SD 50.9 +/- 32.1 days). By using multiway contingency table analysis it was found that in the more severe cases of whooping cough vaccination significantly shortened the illness (p less than 0.005) and reduced the number of coughing spasms (p less than 0.025). The protective effect of the vaccine was most notable in modifying infectivity within the family: 19% of vaccinated family contacts of index patients in whom the disease had been confirmed bacteriologically developed the disease when exposed to it compared with 72% of non-vaccinated contacts (p less than 0.001). These results show that whooping cough vaccination modifies the clinical illness and offers a worthwhile degree of protection to children exposed to the disease.     

Immunisation in a curative setting.

OBJECTIVE--To study the uptake of vaccination offered to women and children attending a curative health facility. DESIGN--Prospective survey over eight months of the uptake of vaccination offered to unimmunised women and children attending a diarrhoeal treatment centre as patients or attendants. SETTING--The International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. SUBJECTS--An estimated 19,349 unimmunised women aged 15 to 45 and 17,372 children attending the centre for treatment or accompanying patients between 1 January and 31 August 1989. MAIN OUTCOME MEASURES--The number of women and children who were unimmunised or incompletely immunised was calculated and the percentage of this target population accepting vaccination was recorded. RESULTS--7530 (84.2%) Of 8944 eligible children and 7730 (40.4%) of 19,138 eligible women were vaccinated. Of the children, 63.8% were boys, 75.9% were aged under 1 year, and 23.0% were aged 1 to 2 years. The estimated number of missed opportunities for vaccination was 716 among the children (8.0% of the target population) and 11,408 among the women (59.6% of those eligible). CONCLUSION--It is possible to establish immunisation services at a health facility treating acutely ill patients.     

Efficacy of pertussis vaccination in England. Report from the PHLS Epidemiological Research Laboratory and 21 area health authorities.

A national assessment of the efficacy of pertussis vaccination was made in 21 area health authorities in England. Notification rates for children given either three doses of diphtheria/tetanus/pertussis vaccine or diphtheria/tetanus vaccine were studied during the two and a half-year period January 1978-June 1980. A survey of home circumstances showed that the two vaccine groups could be validly compared. Home visits were made to assess the severity of the illness, the attack rates in home contacts, and to take pernasal swabs. Pertussis vaccination was found to be of outstanding value in preventing serious disease. Nevertheless, its effect in controlling whooping cough is limited by the fact that protection for home contacts is less satisfactory, and by the occurrence of mild cases in vaccinated children which may contribute to the spread of the disease.     

Etiology, clinical manifestations, and epidemiology in community-acquired respiratory infection in children in the Khabarovsk region

Clinico-epidemiological analysis and etiological verification of the outbreak of respiratory infection among school children in a rural district of the Khabarovsk territory, registered in spring 1997, were made. According to clinical signs, one-third of the patients had whooping cough, while the rest of the children exhibited the signs of respiratory infection with the symptoms of longering bronchitis. A half of the children had not been vaccinated against whooping cough, as they had been given injections of adsorbed DT vaccine with reduced antigen content. Etiologically, the diagnosis of whooping cough was confirmed in 57% of the patients with 47.4% of them having Bordetella pertussis monoinfection and 52.6% having mixed infection, mainly in combination with chlamydiosis. Whooping cough took an abnormal course under these circumstances. Treatment with erythromycin produced a good effect.     

Severity of notified whooping cough.

An analysis was made of the severity of over 8000 cases of whooping cough notified from October 1974 to March 1975. Ten per cent of these patients were admitted to hospital and there were 10 deaths. Severity was directly related to age, the disease being most severe in children under 1 year, especially those under 6 months. There was some evidence that previous vaccination reduced the severity of the disease, but the vaccination programme does not cover very young children, and for them whooping cough is a dangerous disease.     

Injury by hypertonic phosphate enema.

Over a 2-year period 67 strains of Bordetella pertussis were identified in 231 single specimens of nasopharyngeal secretions submitted from patients suspected to have whooping cough in the National Capital Region; 89.5% of the identifications were made by culture. Serotype 1,3 was predominant. At least 75% of the patients with bacteriologically confirmed whooping cough had not been fully immunized. There was no evidence that adenoviruses or other viruses played any important etiologic role in the 204 cases of whooping cough or whooping cough syndrome studied virologically.     

Protection against pertussis by immunisation.

Review of all 126 children admitted to the communicable diseases unit with whooping cough during the epidemic in 1978 showed that two had received two doses of triple vaccine and only one had had full primary immunisation against the disease. None of these three children suffered complications of the disease. Of the 123 children who had not been immunised against pertussis, however, 66 had had one or more complications. In Birmingham the dramatic decline in immunisation against pertussis has been accompanied by a fall in acceptance rates for diphtheria and tetanus immunization. Nevertheless, of the 62 children aged over 1 year in this series, 41 had been so immunised. These findings suggest that the apparently positive decision by parents to omit pertussis immunisation was misplaced, since immunisation does protect against the more serious complications of the disease. Furthermore, there is no firm evidence that pertussis immunisation of children without specific contraindications is associated with serious adverse reactions.     

A decade of diabetes: keeping children out of hospital.

OBJECTIVES--To document the number of children aged less than 15 years who developed diabetes and were managed within one large health district, and to evaluate the outcome of those children managed without hospital admission at diagnosis. DESIGN--A retrospective study over 1979-88, when a paediatrician and a physician with special interests in childhood diabetes initiated joint clinics. Data collected from the district diabetes register and files of consultants and health visitors specialising in diabetes. SETTING--Referral of children to consultants in Leicestershire (total population 863,000). MAIN OUTCOME MEASURES--The proportion of children managed without hospital admission, comparison of readmission rates and glycated haemoglobin concentrations between children admitted and those not admitted. RESULTS--Over 10 years 236 children aged 10-14 years developed diabetes (annual incidence rate 12.8/100,000 child population (95% confidence interval 11.3 to 14.7)). In total 138 were not admitted to hospital but received supervised management based at home. Admitted children were younger or acidotic or their family doctors did not contact the diabetes team. Duration of admission declined from seven days in 1979-80 to three days in 1987-8. Ninety two were not admitted to hospital during the 10 years for any reason. Significantly fewer children who received management at home were readmitted for reasons related to diabetes than the group treated in hospital (30 (22%) v 40 (41%); p = 0.004). Concentrations of glycated haemoglobin were no different between the two groups. CONCLUSIONS--Children with newly diagnosed diabetes may be safely and effectively managed out of hospital. Domiciliary or community based management depends on the commitment of consultants specialising in diabetes working in close cooperation with general practitioners, specialist nurses in diabetes, and dietitians.     

Growth retardation in weight and catch-up growth following infection by measles and whooping cough among babies of rural Zaire (Lake Tumba)

This study has shown that measles and whooping cough affect growth in weight among babies of rural Zaire (Lake Tumba). The average loss in weight due to measles, is more than twice the amount due to whooping cough. However, the time needed to regain the original growth channel after infection by measles, is about half the time needed to fully catch up after whooping cough. The amount of weight loss is proportional to the child's weight at the onset of the disease. There is no difference in the susceptibility to lose weight after measles or whooping cough, between boys and girls, nor between Oto and Twa. This study has also shown that the effect of measles and whooping cough on the growth in weight, is independent of the season of the hear, although the incidence of these diseases showed a significant seasonal pattern. Finally, this study gives evidence for the fact that the incidence of weight loss one month after the onset of measles or whooping cough is age-related.     

Incidence of insulin dependent diabetes in England: a study in the Oxford region, 1985-6.

OBJECTIVE--To determine the incidence of insulin dependent diabetes mellitus up to the age of 21 in a geographically defined population in England with independent validation of completeness of case ascertainment. DESIGN--Prospective registration of newly diagnosed cases supplemented by centralised hospital discharge records and death certificates. Validation of ascertainment from general practitioners. SETTING--Oxford Regional Health Authority area (population 2.4 million). PATIENTS--All patients with insulin dependent diabetes diagnosed below age 21 during 1985-6 and resident in the region at the time of diagnosis. INTERVENTIONS--None. END POINT--Validation of a method of case ascertainment for assessing temporal variation in incidence of insulin dependent diabetes. MEASUREMENTS AND MAIN RESULTS--The overall yearly incidence of newly diagnosed insulin dependent diabetes mellitus in people under 21 was 15.6 cases/100,000 (95% confidence interval 13.6 to 17.6). Among males the incidence was 16.8 cases (14.0 to 19.7)/100,000 and among females 14.3 cases (11.6 to 17.1)/100,000. The highest incidence, in the 10-14 year age group, was 26.4 (20.9 to 31.8) new cases/100,000 population yearly. Case ascertainment was greater than 95%. CONCLUSIONS--The incidence of insulin dependent diabetes in England is considerably higher than reported from large scale studies. It is consistent with described patterns of geographical variation. The figures provide a baseline for assessing temporal change.     

Whooping-cough vaccine. Statement by Joint Committee on Vaccination and Immunization of the Central Health Services Council and the Scottish Health Service Planning Council.

In 1974 it was recommended that pertussis vaccine should continue to be offered in a triple vaccine together with diphtheria and tetanus vaccines. Further data on the prevalence of whooping cough and the incidence of adverse reactions have shown no reason to change this policy; the hazard of whooping cough remains greater than that of immunization.     

Respiratory sequelae of whooping cough. Swansea Research Unit of the Royal College of General Practitioners.

Eight hundred and thirteen children who had had whooping cough when under 5 years of age in the 1977-9 epidemic were compared with a control group roughly four and a half years later, each child being matched by age and sex and from the same class in school. The index group showed long term respiratory sequelae of whooping cough--namely, deterioration in lung function, increase in respiratory symptoms, and increased admission to hospital for both upper and lower respiratory conditions. Asthma was significantly more common in the index group, suggesting that asthma was being regarded as a contraindication to pertussis vaccination. Only 3.5% of the asthmatic children in the index group had been vaccinated as against 29.1% of the controls.     

Estimating the disease burden of 2009 pandemic influenza A(H1N1) from surveillance and household surveys in Greece

Background

The aim of this study was to assess the disease burden of the 2009 pandemic influenza A(H1N1) in Greece.

Methodology/Principal Findings

Data on influenza-like illness (ILI), collected through cross-sectional nationwide telephone surveys of 1,000 households in Greece repeated for 25 consecutive weeks, were combined with data from H1N1 virologic surveillance to estimate the incidence and the clinical attack rate (CAR) of influenza A(H1N1). Alternative definitions of ILI (cough or sore throat and fever>38°C [ILI-38] or fever 37.1–38°C [ILI-37]) were used to estimate the number of symptomatic infections. The infection attack rate (IAR) was approximated using estimates from published studies on the frequency of fever in infected individuals. Data on H1N1 morbidity and mortality were used to estimate ICU admission and case fatality (CFR) rates. The epidemic peaked on week 48/2009 with approximately 750–1,500 new cases/100,000 population per week, depending on ILI-38 or ILI-37 case definition, respectively. By week 6/2010, 7.1%–15.6% of the population in Greece was estimated to be symptomatically infected with H1N1. Children 5–19 years represented the most affected population group (CAR:27%–54%), whereas individuals older than 64 years were the least affected (CAR:0.6%–2.2%). The IAR (95% CI) of influenza A(H1N1) was estimated to be 19.7% (13.3%, 26.1%). Per 1,000 symptomatic cases, based on ILI-38 case definition, 416 attended health services, 108 visited hospital emergency departments and 15 were admitted to hospitals. ICU admission rate and CFR were 37 and 17.5 per 100,000 symptomatic cases or 13.4 and 6.3 per 100,000 infections, respectively.

Conclusions/Significance

Influenza A(H1N1) infected one fifth and caused symptomatic infection in up to 15% of the Greek population. Although individuals older than 65 years were the least affected age group in terms of attack rate, they had 55 and 185 times higher risk of ICU admission and CFR, respectively.     

Intensity of the epidemic process of whooping cough under conditions of mass immunization over a period of many years

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.     

Prospective study of bacterial meningitis in North East Thames region, 1991-3, during introduction of Haemophilus influenzae vaccine.

OBJECTIVE--To describe the epidemiology of primary bacterial meningitis in the North East Thames region over a three year period before and during the introduction of the vaccine for Haemophilus influenzae type b. DESIGN--Analysis of information on cases of primary bacterial meningitis identified by microbiology laboratories in the region, with collection of case data by questionnaire. MAIN OUTCOME MEASURES--Annual incidence rates for types of meningitis according to age and ethnic group. RESULTS--The annual incidence rates for the three major causes of bacterial meningitis in the general population were 1.9/100,000 for Neisseria meningitidis, 1.6/100,000 for Haemophilus influenzae before vaccination, and 1.0/100,000 for Streptococcus pneumoniae. Higher rates of H influenzae meningitis were found in Asians compared with white people (3.6/100,000 v 1.5/100,000, P = 0.01). As a result of the vaccine programme introduced in October 1992 the number of cases of H influenzae meningitis in children under 5 years has fallen by 87%. CONCLUSIONS--Bacterial meningitis is a serious problem especially in preschool children. There are differences in the incidence of some causes of bacterial meningitis in different ethnic groups; with H influenzae type b being significantly more common among black and Asian people than among white people. The immunisation programme for H influenzae type b in the North East Thames region has been successful in reducing the incidence of this type of meningitis in Asian and white populations. The numbers were too small to evaluate in the black population.