Measles immunity and vaccination policy in Catalonia

The prevalence of antibodies against measles in a representative sample of the school population in Catalonia was established and the results compared with previous studies. The study was carried out in 1996 using blood samples obtained from schoolchildren aged 6-7 years, 10-11 years, 13 14 years and 15-16 years. 1231 schoolchildren were studied. The global prevalence of antibodies was 96.3%, and a considerable increase was observed with respect to the prevalence in 1986 (89.4%). The level of antibodies was 94% at 6-7 years and 10-11 years, 99.7% at 13-14 years and 98.3% at 15 16 years. These data would suggest the advancement of the administration of the second dose of measles-mumps rubella vaccine to 4 6 years instead of at 11 years.     

Measles dynamics and vaccination diffusion

Although numerous mathematical models focusing on measles dynamics have been proposed in the literature, efforts in this area have concentrated essentially on the mechanisms of measles propagation. If present, vaccination diffusion is treated as an exogenous factor. Here we propose a model focused on the course of measles in France in which the mechanisms of vaccination diffusion are explicitly modeled. The parameters in this model are estimated by an original method based on an expectation-maximization algorithm. This model gives indications of the way in which measles propagation and vaccination diffusion interact. It also allows discussion of the possibility of eliminating this disease in France in the near future.     

Evaluation of smallpox vaccination policy.

During 1978 and 1979 the Global Commission for the Certification of Smallpox Eradication will proceed with verification of smallpox eradication in 31 countries. If current surveillance activities do not discover any further cases before the end of 1979, the world will be declared smallpox free. However, the recent occurrence of two laboratory associated smallpox cases in Birmingham, England, revealed that the stocks of variola virus held in at least 12 laboratories in the world pose a real danger to the achievement of smallpox eradication and efforts are being made to reduce the number of laboratories retaining the virus to not more than 4—all WHO collaborating centres—by 1980. Scientific data indicate the unlikelihood of smallpox recurring once it has been eradicated from the human population, although further confirmatory studies are continuing. If the Global Commission verifies the eradication of smallpox, continuation of smallpox vaccination will be unjustifiable in view of its severe complications, however infrequent, and the expected global savings that would result from the termination of vaccination programmes.     

Measles vaccination using a microneedle patch

Measles vaccination programs would benefit from delivery methods that decrease cost, simplify logistics, and increase safety. Conventional subcutaneous injection is limited by the need for skilled healthcare professionals to reconstitute and administer injections, and by the need for safe needle handling and disposal to reduce the risk of disease transmission through needle re-use and needlestick injury. Microneedles are micron-scale, solid needles coated with a dry formulation of vaccine that dissolves in the skin within minutes after patch application. By avoiding the use of hypodermic needles, vaccination using a microneedle patch could be carried out by minimally trained personnel with reduced risk of blood-borne disease transmission. The goal of this study was to evaluate measles vaccination using a microneedle patch to address some of the limitations of subcutaneous injection. Viability of vaccine virus dried onto a microneedle patch was stabilized by incorporation of the sugar, trehalose, and loss of viral titer was less than 1 log₁₀(TCID₅₀) after storage for at least 30 days at room temperature. Microneedle patches were then used to immunize cotton rats with the Edmonston-Zagreb measles vaccine strain. Vaccination using microneedles at doses equaling the standard human dose or one-fifth the human dose generated neutralizing antibody levels equivalent to those of a subcutaneous immunization at the same dose. These results show that measles vaccine can be stabilized on microneedles and that vaccine efficiently reconstitutes in vivo to generate a neutralizing antibody response equivalent to that generated by subcutaneous injection.     

Measles in 2010. Knowledge and vaccination status of medical students

Objectives

In 2002, the WHO Regional Office for Europe developed a strategic plan for measles in the WHO European Region. WHO recommends that at least 95% of children receive two doses of measles vaccine. This plan targeted the elimination of measles for the year 2010 and is supported by the Federal Republic of Germany.

Methods

Questionnaire survey, serological tests and check-up of the certificates of vaccination were offered to second year medical students of Goethe University Frankfurt/Main, Germany.

Results

Only 62.3% of medical students had received two doses of measles vaccine. Serological data showed that 23.1% were not immune against measles. Important gaps of knowledge were identified in the knowledge test of the survey; less than one third of the students (n=95/324) were able to answer more than 50% of the questions correctly.

Discussion

The suboptimum measles-vaccination coverage shows that the goal of eliminating measles will not be met across Europe by the target year 2010. Both occupational and public health measures need to make sure that vaccination programs should achieve a minimum of 95% coverage with two doses. In addition, the obligation to notify the authorities even of suspected cases serve the same purpose and measures to improve the knowledge of medical students are required. Consequent surveillance systems are necessary to investigate chains of measles infections. Healthcare workers play a decisive role in this issue.     

Measles vaccination and childhood mortality in rural Bangladesh

To ascertain whether measles vaccination was associated with reduced mortality rates in rural Bangladeshi children, the authors conducted a case-control study in four contiguous areas, two of which had participated in an intensive measles vaccination program which began in the spring of 1982. Cases were 536 children who had died in the four-area region at the age of 10-60 months between April 1982 and December 1984. Two age- and sex-matched controls were selected from the four-area region for each case; each control had survived at least through the date of death of the matched case. Measles vaccination was associated with a 36% (95% confidence interval 21%-48%) proportionate reduction in the overall rate of death and a 57% (95% confidence interval 43%-67%) reduction in the rate of deaths directly attributed to measles or ascribed to diarrhea, respiratory illness, or malnutrition. The association of measles vaccination and reduced mortality remained unchanged after the authors restricted controls to children who had survived at least one year after the deaths of their matched cases. Moreover, children vaccinated in 1982 exhibited a sustained reduction in the rate of death in 1983 and 1984. The authors concluded that measles vaccination was associated with a pronounced and sustained reduction in the rate of death among children in this study.     

Measles and measles vaccination in an African village

Over the last five years, a number of reports have appeared drawing attention to the serious results of measles in young West African children. This is borne out by observations over a three-year period on children in the village of Imesi, which showed measles to be a severe and often fatal disease. The original live attenuated measles vaccine developed by Enders has been shown to give good protection and, in combination with immune serum, has been widely used in the USA. However, the need to combine it with immune serum severely limits its usefulness, owing to the small quantities of serum available and the high cost. In the present study, the reaction produced by the original vaccine with immune serum was compared with the reaction produced by a further attenuated vaccine without serum. The latter gave significantly fewer and less severe reactions, but produced a satisfactory serological response. This new vaccine should facilitate large-scale immunization of children in areas such as West Africa where protection against measles is urgently required.     

Measles vaccination of macaques by dry powder inhalation

Measles vaccination via the aerosol route has proven effective under field conditions, using vaccine reconstituted prior to nebulization. Inhalation of a dry powder aerosol vaccine would have additional benefits, including easier logistics of administration, reduced cold chain dependence and the potential of single dose administration. We have evaluated two candidate dry powder measles vaccine formulations in macaques. Specific immune responses were demonstrated, but levels of immunity were lower than in animals vaccinated by injection or by nebulized aerosol. These studies provide proof of principle that dry powder inhalation is a possible route for measles vaccination, but suggest that either the vaccine formulation or the method of delivery need to be improved for a better immune response.     

Measles in developing countries. Part II. The predicted impact of mass vaccination

A mathematical model is developed to mimic the transmission dynamics of the measles virus in communities in the developing world with high population growth rates and high case fatality rates. The model is used to compare the impacts of different mass vaccination programmes upon morbidity and mortality arising from infection by measles virus. Analyses identify three conclusions of practical significance to the design of optimal vaccination programmes. First, there is no single optimum age at which to vaccinate children for all urban and rural communities in developing countries. For a given community the best age at which to vaccinate depends critically on the age distribution of cases of infection prior to the introduction of control measures. Second, numerical studies predict that the introduction of mass vaccination will induce a temporary phase of very low incidence of infection before the system settles to a new pattern of recurrent epidemics. Mass vaccination acts to lengthen the inter-epidemic period in the post-vaccination period when compared with that prevailing prior to control. Third, numerical simulations suggest that two-phase and two-stage vaccination programmes are of less benefit than one-stage programmes (achieving comparable coverage) aimed at young children. The paper ends with a discussion of the needs for: improved programmes of data collection; monitoring of the impact of current vaccination programmes; and the development of models that take account of viral transmission dynamics, host demography and economic factors.     

Measles epidemiology in Catalonia (Spain): implications for a regional vaccination programme.

BACKGROUND: To analyse progress in measles control it is recommended that immunization programmes be evaluated by means of specific epidemiological disease surveillance. The aim of the study was to analyse a series of measles cases in Catalonia in the light of vaccination records. METHODS: Cases were detected by means of the epidemiological surveillance system and then surveyed for information on: age, sex, clinical symptoms, laboratory confirmation, record of vaccination, place of infection and possible outbreak-related links. The relationship between 'record of vaccination' and the remaining variables was determined using the adjusted odds ratio (OR) and its 95% confidence interval (CI). RESULTS: The epidemiological survey confirmed that 82.2% of patients (171/208) fulfilled the case criteria. In the multivariate analysis, lack of record of vaccination was associated with age groups < 5 years (OR = 4.0; 95% CI: 1.4-11.8) and > 14 years (OR = 19.2; 95% CI: 5.1-220.5). CONCLUSIONS: Improvement in vaccination coverage at 15 months and the introduction of vaccination-status monitoring at school-entry age and among those aged > 14 years on entry into the job market, university or military service could contribute to the elimination of measles.