Measles vaccines: a review of adverse events

Novel ablative laser mediated transdermal immunization for microparticulate measles vaccine

With the need for safe and efficacious vaccines which could be administered via non-invasive procedure, alternatives to traditional injectables vaccines are sought after. The present study aimed to develop the microparticulate formulation of measles vaccine and explore the feasibility of transdermal delivery via ablative laser mediated skin microporation. Transdermal route offers several advantages including painless immunization and ease of administration. We propose to use P.L.E.A.S.E. ablative laser for transdermal immunization of the microparticulate measles vaccine. This laser emits energy at 2940 µm, enabling cold ablation. This creates the micropores of defined size for delivery of vaccines into the skin. We compared the efficacy of transdermal immunization using the particulate formulation of the vaccine to that of traditional subcutaneous immunization using soluble and particulate vaccine. The microparticles were formulated using the biocompatible and biodegradable bovine serum albumin (BSA)-based polymer matrix. These vaccine microparticles were non-cytotoxic to the antigen presenting cells (APCs) and could effectively stimulate the innate immune response, confirmed by release of nitric oxide (NO) from the Griess's assay. The APCs when exposed to vaccine microparticles also showed a significantly higher expression of antigen-presenting molecules, MHC I and MHC II, and their co-stimulatory molecules, CD80 and CD40 as compared to the blank microparticles. The microparticulate measles vaccine was evaluated in vivo in the murine model. We compared the serum IgG and IgM levels in the mice receiving the vaccine subcutaneously and transdermally post-immunization. The results revealed that transdermal immunization with microparticulate vaccine is as efficient as the traditional subcutaneous administration.

Accounting for indirect protection in the benefit-risk ratio estimation of rotavirus vaccination in children under the age of 5 years, France, 2018

Background Rotavirus is a major cause of severe gastroenteritis in children worldwide. The disease burden has been substantially reduced in countries where rotavirus vaccines are used. Given the risk of vaccine-induced intussusception, the benefit–risk balance of rotavirus vaccination has been assessed in several countries, however mostly without considering indirect protection effects. Aim We performed a benefit–risk analysis of rotavirus vaccination accounting for indirect protection in France among the 2018 population of children under the age of 5 years. Methods To incorporate indirect protection effects in the benefit formula, we adopted a pseudo-vaccine approach involving mathematical approximation and used a simulation design to provide uncertainty intervals. We derived background incidence distributions from quasi-exhaustive health claim data. We examined different coverage levels and assumptions regarding the waning effects and intussusception case fatality rate. Results With the current vaccination coverage of < 10%, the indirect effectiveness was estimated at 6.4% (+/− 0.4). For each hospitalisation for intussusception, 277.0 (95% uncertainty interval: (165.0–462.1)) hospitalisations for rotavirus gastroenteritis were prevented. Should 90% of infants be vaccinated, indirect effectiveness would reach 57.9% (+/− 3.7) and the benefit–risk ratio would be 192.4 (95% uncertainty interval: 116.4–321.3). At a coverage level of 50%, indirect protection accounted for 27% of the prevented rotavirus gastroenteritis cases. The balance remained in favour of the vaccine even in a scenario with a high assumption for intussusception case fatality. Conclusions These findings contribute to a better assessment of the rotavirus vaccine benefit–risk balance.

Treatment of latent infection to achieve tuberculosis elimination in low-incidence countries

In a Perspective for the Tuberculosis Special Issue, Kevin Schwartzman and colleagues discuss the choices and implications for personal versus public health benefits when pursuing tuberculosis elimination in low-incidence countries.

Revealing Measles Outbreak Risk With a Nested Immunoglobulin G Serosurvey in Madagascar

Madagascar reports few measles cases annually and high vaccination campaign coverage. However, the underlying age profile of immunity and risk of a measles outbreak is unknown. We conducted a nested serological survey, testing 1,005 serum samples (collected between November 2013 and December 2015 via Madagascar’s febrile rash surveillance system) for measles immunoglobulin G antibody titers. We directly estimated the age profile of immunity and compared these estimates with indirect estimates based on a birth cohort model of vaccination coverage and natural infection. Combining these estimates of the age profile of immunity in the population with an age-structured model of transmission, we further predicted the risk of a measles outbreak and the impact of mitigation strategies designed around supplementary immunization activities. The direct and indirect estimates of age-specific seroprevalence show that current measles susceptibility is over 10%, and modeling suggests that Madagascar may be at risk of a major measles epidemic.

Cell culture-based viral vaccines: current status and future prospects

Cell culture-based viral vaccines are used globally to immunize humans against infections. The cell culture is continuous process of developing substrates for the safe production of viral vaccines. However, increased global demand and strict safety rules for novel vaccines to control and eradicate viral diseases have forced researchers and manufacturers toward cell culture-based vaccines. The choice of cell substrate is a critical step that cannot be generalized for every vaccine formulation, therefore, manufacturers intend to optimize the required processes for particular applications. The recently established cell lines, innovative bioreactor concepts and cultivation schemes are necessary to increase the potential of vaccine production. In this review, we have focused on current cell culture-based viral vaccines and their future prospects.

Live attenuated vaccines: Historical successes and current challenges

Live attenuated vaccines against human viral diseases have been amongst the most successful cost effective interventions in medical history. Smallpox was declared eradicated in 1980; poliomyelitis is nearing global eradication and measles has been controlled in most parts of the world. Vaccines function well for acute diseases such as these but chronic infections such as HIV are more challenging for reasons of both likely safety and probable efficacy. The derivation of the vaccines used has in general not been purely rational except in the sense that it has involved careful clinical trials of candidates and subsequent careful follow up in clinical use; the identification of the candidates is reviewed.

Subacute sclerosing panencephalitis: A clinical appraisal

Introduction:

Subacute sclerosing panencephalitis (SSPE) is a rare chronic, progressive encephalitis affecting primarily children and young adults, caused by a persistent infection of immune resistant measles virus. The aim of the present study is to describe the clinical profile and natural history of patients with SSPE.

Methods:

We collected data of patients with SSPE during 2004-2010 who fulfilled Dyken's criteria. We analyzed demographical, clinical, electrophysiological, and imaging features.

Results:

Study included 34 patients, 26 (76.5%) males with age of onset from 3 to 31 years. Twenty one patients were below 15 years of age formed childhood SSPE and 13 above 15 years of age constituted adult onset group. 85.3% had low-socioeconomic status. Eleven received measles vaccination and seven were unvaccinated. 59.9% patients had measles history. Most common presenting symptom was scholastic backwardness (52.5%) followed by seizures (23.5%). Three patients each had cortical blindness, macular degeneration, decreased visual acuity, and optic atrophy. Electroencephalographic (EEG) showed long interval periodic complexes and cerebrospinal fluid anti-measles antibody was positive in all. Magnetic resonance imaging was done in 70.5% with was abnormal in 52.5%. Mean incubation period of SSPE after measles was 9.6 years. The follow-up duration was 1-10 years, (average of 2 years). Only one patient died from available data of follow-up, 9 were stable and 10 deteriorated in the form of progression of staging.

Conclusion:

SSPE is common in low-socioeconomic status. The profile of adult onset did not differ from childhood onset SSPE, except for a longer interval between measles infection and presence of the ophthalmic symptom as presenting feature in adult onset group.

Measles virus infection of the CNS: human disease, animal models, and approaches to therapy

Viral infections of the central nervous system(CNS) mostly represent clinically important, often life-threatening complications of systemic viral infections. After acute measles, CNS complications may occur early (acute postinfectious measles encephalitis, APME) or after years of viral persistence (subacute sclerosing panencephalitis, SSPE). In spite of a presumably functional cell-mediated immunity and high antiviral antibody titers, an immunological control of the CNS infection is not achieved in patients suffering from SSPE. There is still no specific therapy for acute complications and persistent MV infections of the CNS. Hamsters, rats, and (genetically unmodified and modified) mice have been used as model systems to study mechanisms of MV-induced CNS infections. Functional CD4+ and CD8+ T cells together with IFN-gamma are required to overcome the infection. With the help of recombinant measles viruses and mice expressing endogenous or transgenic receptors, interesting aspects such as receptor-dependent viral spread and viral determinants of virulence have been investigated. However, many questions concerning the lack of efficient immune control in the CNS are still open. Recent research opened new perspectives using specific antivirals such as short interfering RNA (siRNA) or small molecule inhibitors. Inspite of obvious hurdles, these treatments are the most promising approaches to future therapies.

Subacute sclerosing panencephalitis: an update

Subacute sclerosing panencephalitis (SSPE) is a chronic encephalitis occurring after infection with measles virus. The prevalence of the disease varies depending on uptake of measles vaccination, with the virus disproportionally affecting regions with low vaccination rates. The physiopathology of the disease is not fully understood; however, there is evidence that it involves factors that favour humoral over cellular immune response against the virus. As a result, the virus is able to infect the neurons and to survive in a latent form for years. The clinical manifestations occur, on average, 6 years after measles virus infection. The onset of SSPE is insidious, and psychiatric manifestations are prominent. Subsequently, myoclonic seizures usually lead to a final stage of akinetic mutism. The diagnosis is clinical, supported by periodic complexes on electroencephalography, brain imaging suggestive of demyelination, and immunological evidence of measles infection. Management of the disease includes seizure control and avoidance of secondary complications associated with the progressive disability. Trials of treatment with interferon, ribavirin, and isoprinosine using different methodologies have reported beneficial results. However, the disease shows relentless progression; only 5% of individuals with SSPE undergo spontaneous remission, with the remaining 95% dying within 5 years of diagnosis.

N-(3-Cyanophenyl)-2-phenylacetamide, an effective inhibitor of morbillivirus-induced membrane fusion with low cytotoxicity

Based on the structural similarity of viral fusion proteins within the family Paramyxoviridae, we tested recently described and newly synthesized acetanilide derivatives for their capacity to inhibit measles virus (MV)-, canine distemper virus (CDV)- and Nipah virus (NiV)-induced membrane fusion. We found that N-(3-cyanophenyl)-2-phenylacetamide (compound 1) has a high capacity to inhibit MV- and CDV-induced (IC(50) μM), but not NiV-induced, membrane fusion. This compound is of outstanding interest because it can be easily synthesized and its cytotoxicity is low [50 % cytotoxic concentration (CC(50)) ≥ 300 μM], leading to a CC(50)/IC(50) ratio of approximately 100. In addition, primary human peripheral blood lymphocytes and primary dog brain cell cultures (DBC) also tolerate high concentrations of compound 1. Infection of human PBMC with recombinant wild-type MV is inhibited by an IC(50) of approximately 20 μM. The cell-to-cell spread of recombinant wild-type CDV in persistently infected DBC can be nearly completely inhibited by compound 1 at 50 μM, indicating that the virus spread between brain cells is dependent on the activity of the viral fusion protein. Our findings demonstrate that this compound is a most applicable inhibitor of morbillivirus-induced membrane fusion in tissue culture experiments including highly sensitive primary cells.

Knowledge synthesis of benefits and adverse effects of measles vaccination: the Lasbela balance sheet

Background

In preparation for a cluster-randomized controlled trial of a community intervention to increase the demand for measles vaccination in Lasbela district of Pakistan, a balance sheet summarized published evidence on benefits and possible adverse effects of measles vaccination.

Methods

The balance sheet listed: 1) major health conditions associated with measles; 2) the risk among the unvaccinated who contract measles; 3) the risk among the vaccinated; 4) the risk difference between vaccinated and unvaccinated; and 5) the likely net gain from vaccination for each condition.

Results

Two models revealed very different projections of net gain from measles vaccine. A Lasbela-specific combination of low period prevalence of measles among the unvaccinated, medium vaccination coverage and low vaccine efficacy rate, as revealed by the baseline survey, resulted in less-than-expected gains attributable to vaccination. Modelled on estimates where the vaccine had greater efficacy, the gains from vaccination would be more substantial.

Conclusion

Specific local conditions probably explain the low rates among the unvaccinated while the high vaccine failure rate is likely due to weaknesses in the vaccination delivery system. Community perception of these realities may have had some role in household decisions about whether to vaccinate, although the major discouraging factor was inadequate access. The balance sheet may be useful as a communication tool in other circumstances, applied to up-to-date local evidence.

Dynamic interaction of the measles virus hemagglutinin with its receptor signaling lymphocytic activation molecule (SLAM, CD150)

The interaction of measles virus with its receptor signaling lymphocytic activation molecule (SLAM) controls cell entry and governs tropism. We predicted potential interface areas of the measles virus attachment protein hemagglutinin to begin the investigation. We then assessed the relevance of individual amino acids located in these areas for SLAM-binding and SLAM-dependent membrane fusion, as measured by surface plasmon resonance and receptor-specific fusion assays, respectively. These studies identified one hemagglutinin protein residue, isoleucine 194, which is essential for primary binding. The crystal structure of the hemagglutinin-protein localizes Ile-194 at the interface of propeller blades 5 and 6, and our data indicate that a small aliphatic side chain of residue 194 stabilizes a protein conformation conducive to binding. In contrast, a quartet of residues previously shown to sustain SLAM-dependent fusion is not involved in binding. Instead, our data prove that after binding, this quartet of residues on propeller blade 5 conducts conformational changes that are receptor-specific. Our study sets a structure-based stage for understanding how the SLAM-elicited conformational changes travel through the H-protein ectodomain before triggering fusion protein unfolding and membrane fusion.

Communicable respiratory threats in the ED: tuberculosis, influenza, SARS, and other aerosolized infections

Respiratory infections are the most common communicable infectious diseases. EDs are the front line for patients with respiratory infections because of their acute nature and because the ED is the principal site of health care for those at highest risk. These diseases include influenza, tuberculosis, and measles, together accounting for 25% of infectious causes of death worldwide. These are emerging and biothreat agents that follow the same route of transmission, such as pneumonic plague. We discuss epidemiology, pathogenesis, diagnosis, and treatment of each agent. Emphasis is on the ED's role as a public health prevention arena, with attention to education and disease prevention, early identification of disease in patients at risk, and reduction of illnesses.

Economic evaluation of measles catch-up and follow-up campaigns in Afghanistan in 2002 and 2003

This paper assesses the cost-effectiveness of, and the return on the investment in, the 2002 catch-up and the 2003 follow-up measles campaigns in Afghanistan from the perspective of the donor. The catch-up campaign targeted nearly 12 million children aged between six months and 12 years, while the follow-up campaign targeted over five million children aged between 9 and 59 months. Both campaigns successfully vaccinated approximately 96 per cent of the respective target populations, and are expected to avert an estimated 301,000 measles deaths over the next 10 years. The average cost per dose of measles vaccine delivered was USD 0.40. The cost per death prevented is USD 23.6, assuming a case fatality rate of 10 per cent and a discount rate of three per cent. With more than 42,000 measles deaths avoided for every one million US dollars spent, the campaigns are an excellent public health investment for precluding childhood mortality in a country affected by a complex emergency.

Public fear of vaccination: separating fact from fiction

During the last two centuries, the world has seen a substantial increase in the number and availability of vaccines for the prevention of infectious disease. Smallpox vaccine remains the most celebrated vaccine-related achievement in human history, but worldwide reductions in many other diseases including measles, mumps, rubella, polio, diphtheria, and whooping cough (Bordetella pertussis) also illustrate the power of vaccination in controlling outbreaks of contagious diseases. Ironically, as advances in vaccination successfully limit disease outbreaks, the impact that these infectious agents once had on society becomes marginalized. Public confidence in vaccination may erode because of real or perceived risks associated with immunization, and this in turn may lead to lower vaccination coverage and loss of herd immunity. Here, we will discuss some of the elements associated with public perceptions and fear of vaccination and place these into the context of how deadly several vaccine-preventable childhood diseases can be if vaccination coverage is insufficient.

Economic analysis of the 1996–1997 mass measles immunization campaigns in South Africa

To evaluate economic implications of conducting a "catch-up" measles vaccination campaign, we conducted an economic analysis of the 1996-1997 measles immunization campaign in two provinces of South Africa comparing the baseline two-dose routine immunization program to the combined vaccination strategy (routine two-dose immunization program, plus the 1996-1997 campaign). The study findings indicate that the 1996-1997 mass measles immunization campaign was cost-effective in both study provinces, and cost-saving in the province with higher pre-campaign disease incidence and lower routine vaccination coverage. An early investment in effective vaccination strategies that rapidly reduce disease burden apparently results in better returns, both epidemiologically and economically.

Acute fulminant subacute sclerosing panencephalitis with absent measles and PCR studies in cerebrospinal fluid

This report describes an atypical case of rapidly progressive subacute sclerosing panencephalitis presenting as transient visual agnosia and myoclonus in a 14-year-old male. There were no typical periodic complexes in serial electroencephalographic monitoring; cerebrospinal fluid measles antibody titer was negative. The diagnosis was made by molecular and histologic examination of open brain biopsy tissue.

Detection of species-specific helicobacter ribosomal DNA in intestinal biopsy samples from a population-based cohort of patients with ulcerative colitis

The inflammatory bowel diseases are considered an abnormal host immune response to an environmental stimulus. Evidence suggests a role for intestinal bacteria in initiating and/or providing an ongoing stimulus for inflammation in inflammatory bowel disease. Helicobacter pylori is the major cause of active chronic gastritis and peptic ulcers in humans and has been linked to gastric carcinoma and lymphoma. Studies in various animal models, particularly mice, have identified enterohepatic Helicobacter species that are capable of causing hepatitis and enterocolitis. We hypothesize that Helicobacter species may have a role in maintaining inflammation in humans with inflammatory bowel disease. In order to investigate this, biopsy specimens were obtained from patients with and without inflammatory bowel disease. DNA was extracted from the tissues and subjected to PCR with primers designed to detect the ribosomal DNA of members of the Helicobacter species. DNA from six biopsy samples from 60 inflammatory bowel disease patients tested positive. This included 5 of 33 ulcerative colitis patients that were positive compared to 0 of 29 age-matched controls (P < 0.04). Sequencing of the bands produced by PCR amplification revealed >or=99% homology with H. pylori. These results indicate that a member of the Helicobacter species may be involved in some cases of ulcerative colitis.

Selectively receptor-blind measles viruses: Identification of residues necessary for SLAM- or CD46-induced fusion and their localization on a new hemagglutinin structural model

Measles virus (MV) enters cells either through the signaling lymphocyte activation molecule SLAM (CD150) expressed only in immune cells or through the ubiquitously expressed regulator of complement activation, CD46. To identify residues on the attachment protein hemagglutinin (H) essential for fusion support through either receptor, we devised a strategy based on analysis of morbillivirus H-protein sequences, iterative cycles of mutant protein production followed by receptor-based functional assays, and a novel MV H three-dimensional model. This model uses the Newcastle disease virus hemagglutinin-neuraminidase protein structure as a template. We identified seven amino acids important for SLAM- and nine for CD46 (Vero cell receptor)-induced fusion. The MV H three-dimensional model suggests (i) that SLAM- and CD46-relevant residues are located in contiguous areas in propeller beta-sheets 5 and 4, respectively; (ii) that two clusters of SLAM-relevant residues exist and that they are accessible for receptor contact; and (iii) that several CD46-relevant amino acids may be shielded from direct receptor contacts. It appears likely that certain residues support receptor-specific H-protein conformational changes. To verify the importance of the H residues identified with the cell-cell fusion assays for virus entry into cells, we transferred the relevant mutations into genomic MV cDNAs. Indeed, we were able to recover recombinant viruses, and we showed that these replicate selectively in cells expressing SLAM or CD46. Selectively receptor-blind viruses will be used to study MV pathogenesis and may have applications for the production of novel vaccines and therapeutics.

Measles and rubella in the World Health Organization European region: diversity creates challenges

Since 1984, the World Health Organization (WHO) European Region has had targets for reducing the burden of a number of communicable diseases. While some countries have already met the targets for interrupting indigenous measles transmission and for reducing the incidence of congenital rubella syndrome to <1 case per 100,000 births, most have not. The cultural and economic diversity of the region present a number of challenges that must be overcome before the regional targets are met. These include social factors, political will, economic costs associated with supplementary campaigns, and more effective communication with health professionals and the public on the benefits and risks associated with immunization. Most WHO European Region member states are expected to use combined measles-mumps-rubella vaccine within the next 5 years. Consultation within the region is occurring on a strategic plan to meet the targets by 2010.

The unfinished measles immunization agenda

Despite achieving and sustaining global measles vaccination coverage of about 80% over the past decade, worldwide measles remains the fifth leading cause of mortality among children aged <5 years. In May 2002, the United Nations Special Session on Children endorsed the goal of reducing measles deaths by half by 2005. Countries and World Health Organization (WHO) regions that adopted aggressive measles control or elimination strategies have shown excellent results. In 2001, countries in the Americas reported an all time low of 537 confirmed measles cases. Substantial progress in measles control has also been achieved in the WHO Western Pacific Region, in seven southern African countries, and in selected countries in WHO European, Eastern Mediterranean, and Southeast Asian regions. The ongoing measles disease burden and availability of safe and effective measles mortality reduction strategies make a compelling case to complete the unfinished agenda of measles immunization.

Monitoring vaccine safety during measles mass immunization campaigns: clinical and programmatic issues

In the planning and implementation of mass immunization campaigns, vaccine delivery has always been a priority. However, safety issues have gained increasingly more attention and grown in importance, and campaign planners must now take them into prime consideration. The World Health Organization has released guidelines to assist with the design and implementation of safety surveillance systems, primarily for developing countries, and these include a new monograph for measles mass campaigns. Experience in the past decade with mass campaigns (primarily in developed countries) shows that measles vaccine performs in these settings as anticipated from pre- and post-licensure studies. Serious adverse events are rare, even under the increased scrutiny extended during a campaign. The experience in developing country settings is growing. The implementation of safety surveillance for mass campaigns offers a unique opportunity for countries to avoid crisis situations and to begin vaccine safety monitoring in routine immunization programs.

Does the MMR vaccine and secretin or its receptor share an antigenic epitope?

In a subgroup of children with autism-spectrum like conditions symptoms seem to appear as a 'regression' (in normal development). It has been postulated that the onset of such autistic symptoms may involve an autoimmune response against the central nervous system and that the antigenic determinant could possibly be gastrointestinal in origin. It has been suggested that the presence of the measles virus and 'autistic enterocolitis' demonstrates the possibility that the MMR triple vaccine may be mediating the inflammation with possible production of antibodies against the virus containing vaccine. Such an antibody may share antigenic determinant to molecules found in the gut. We propose that this may be secretin or its receptor, found in the gut as well as in the central nervous system. The antibody response to the gut may also conceivably occur in the brain at a critical time in development. The modulation of development by secretin may be a static event possibly occurring at a specific time in early childhood development and if it involves an autoimmune response then a disruption in development may result. These hypothesized events can only occur if the MMR vaccine shares antigenic determinants that resemble secretin or any of its receptor types and remains to be studied.

The difficult quest for data on "vanishing" vaccine-preventable infections in Europe: the case of measles in Flanders (Belgium)

We aimed to describe the impact of vaccination on the epidemiology of measles infection in Flanders (Belgium), to document probable vaccination coverage based on this evidence, compare these epidemiological data with those generated by a mathematical model and estimate the costs of morbidity from measles. In contrast to previous analyses, we included the costs of long-term care for sequelae due to encephalitis and subacute sclerosing panencephalitis (SSPE). We estimated the direct health care costs per average measles case at 227, 212, 210, 200 and 194 for the age groups of 0-4, 5-9, 10-14, 15-19 and > or=20 years, respectively. Excluding long-term care lowers these estimates by 22-51%, depending on the age group. By including indirect time costs, we arrive at total costs per measles case of 320, 305, 210, 200 and 625, respectively. In addition to registering vaccination coverage more rigorously in the future, it seems necessary to undertake seroprevalence studies to document the age-specific immunity to measles. By using such information, current vaccination strategies can be adapted to prevent future outbreaks and to help eliminate measles from Europe in an efficient way. We noted throughout that many of the data sources are flawed. Better and accessible data bases are required to improve the reliability of similar studies in the future.

Measles infection of the central nervous system

Central nervous system (CNS) complications occurring early and late after acute measles are serious and often fatal. In spite of functional cell-mediated immunity and high antiviral antibody titers, an immunological control of the CNS infection is not achieved in patients suffering from subacute sclerosing panencephalitis (SSPE). The known cellular receptors for measle virus (MV) in humans, CD46 and CD150 (signaling lymphocyte activation molecule, SLAM), are important components of the viral tropism by mediating binding and entry to peripheral cells. Because neural cells do not express SLAM and only sporadically CD46, virus entry to neural cells, and spread within the CNS, remain mechanistically unclear. Mice, hamsters, and rats have been used as model systems to study MV-induced CNS infections, and revealed interesting aspects of virulence, persistence, the immune response, and prerequisites of protection. With the help of recombinant MV and mice expressing transgenic receptors, questions such as receptor-dependent viral spread, or viral determinants of virulence, have been investigated. However, many questions concerning the human MV-induced CNS diseases are still open.

Will the current measles vaccines ever eradicate measles?

Measles virus is the most infectious transmissible agent causing human disease and has probably been responsible for the deaths of more children than any other single cause. In addition, infection with the natural virus causes many severe complications, including encephalitis, deafness and pneumonia. The introduction of live attenuated vaccines, either singly or as the measles-mumps-rubella combined vaccine, has dramatically reduced the occurrence of disease and in countries where vaccine uptake is high, indigenous disease has been virtually eliminated. Even though the current vaccines are very efficient, they do have their limitations. Children are most at risk during the first year of life and for most of this period, maternal antibodies prevent effective immunization. In addition, the current measles vaccines are relatively heat labile which causes difficulty in tropical areas. In recent years, vaccination rates in some industrial countries have been adversely affected by fears that measles vaccines are linked to inflammatory bowel diseases and autism. Although there is no conclusive evidence to support these fears, they still remain and probably contribute to poor vaccine uptake in some regions and sections of society. Although severe complications from vaccination are extremely rare, mild local reactions are more common. Consequently, in countries where measles is declining or has been eliminated, the fear of side effects of vaccination may encourage the development of vaccines that do not rely on virus replication to take effect.

The average cost of measles cases and adverse events following vaccination in industrialised countries

BACKGROUND

Even though the annual incidence rate of measles has dramatically decreased in industrialised countries since the implementation of universal immunisation programmes, cases continue to occur in countries where endemic measles transmission has been interrupted and in countries where adequate levels of immunisation coverage have not been maintained. The objective of this study is to develop a model to estimate the average cost per measles case and per adverse event following measles immunisation using the Netherlands (NL), the United Kingdom (UK) and Canada as examples.

METHODS

Parameter estimates were based on a review of the published literature. A decision tree was built to represent the complications associated with measles cases and adverse events following immunisation. Monte-Carlo Simulation techniques were used to account for uncertainty.

RESULTS

From the perspective of society, we estimated the average cost per measles case to be US$276, US$307 and US$254 for the NL, the UK and Canada, respectively, and the average cost of adverse events following immunisation per vaccinee to be US$1.43, US$1.93 and US$1.51 for the NL, UK and Canada, respectively.

CONCLUSIONS

These average cost estimates could be combined with incidence estimates and costs of immunisation programmes to provide estimates of the cost of measles to industrialised countries. Such estimates could be used as a basis to estimate the potential economic gains of global measles eradication.

Vaccine safety: risk communication--a global perspective

The complexity of risks connected with both vaccine-preventable diseases as well as with immunization will be discussed and used as the basis for conclusions: -what should be done to avoid damage to current and future immunization programs and -how to improve risk communication. The need for more complete data on true, perceived and unknown immunization risks necessitates strengthening our research capabilities as well as surveillance and vaccine safety programs, and to critically examine the factors influencing public sentiments, taking into account that public perceptions of risk vary depending on the characteristics of risk. A concerted effort is needed to improve benefit and risk communication at all levels. The medical community should play a key role for improved communication.

How should physicians and nurses deal with people who do not want immunizations?

People who do not want immunizations represent a small fraction of the total population. However, they may have significant epidemiologic impact. Reasons for lack of support for immunization include ignorance, fear, contraindication, general opposition based on religion or philosophy, or "informed" opposition. The category of "informed" opposition includes those who have decided, based on reliable information, that the risks of immunization outweigh the benefits in their particular case. It also includes "misinformed" opposition arising from acceptance of unproven allegations about vaccine safety or efficacy. These views may be fostered by media accounts of adverse events alleged to be caused by vaccines. Carefully developed and forthright responses to these issues are needed to assure that people make truly informed immunization decisions.

Safety of routine childhood vaccinations. An epidemiological review

Immunisations have been one of the most cost-effective public health interventions in human history. Despite remarkable progress, several challenges face immunisation programs worldwide. Paradoxically, despite vaccines' clear effectiveness in reducing risks of diseases that were previously widely prevalent and caused substantial morbidity and mortality, current vaccination policies have become increasingly controversial due to concerns about vaccine safety. Vaccines, like other pharmaceutical products, are not entirely risk-free. While most known adverse effects are minor and self-limited, some vaccines have been associated with very rare but serious adverse effects. Because such rare effects are often not evident until vaccines come into widespread use, ongoing surveillance programs to monitor vaccine safety are needed. Such monitoring will be essential if the public is to accept the increasing number of new vaccines made possible by biotechnology. The interpretation of data from vaccine safety research is complex and is associated with some uncertainty. Effectively communicating this uncertainty and continuing to improve understanding of rare risks and risk factors are essential for "mature" immunisation programs to maintain public confidence in immunisations.