The Vaccine Book

Barry R. Bloom,Barry R. Bloom,Paul-Henri Lambert

• Publisher: Academic Press
• Year: 2002
• ISBN:
  9780080542669
• Topic: Medizin
• Subtopic: Infektiologie

The Vaccine Book provides comprehensive information on the current and future world of vaccines. It reveals the scientific opportunities and potential impact of vaccines, including economic and ethical challenges, problems encountered when producing vaccines, how clinical vaccine trials are designed, and how to introduce vaccines into widespread use. Although vaccines are now available for many diseases, there are still challenges ahead for major diseases such as AIDS, tuberculosis, and malaria. The Vaccine Book is designed for students, researchers, public health officials, and all others interested in increasing their understanding of vaccines.Topics unique to this book: * Ethics * Economics * Diseases that could be prevented* Clinical trial designs* Ideas about the future of vaccines* Challenges facing research scientists in the vaccine area* Burden of vaccine-preventable illness and the impact of vaccines* Scientific obstacles to be overcome by existing and new vaccines* Basic mechanisms of host immunity and pathogen interaction with host tissues* New approaches to future vaccines against challenging diseases* Real and perceived safety issues which dominate vaccine development and vaccination policies* Microbial pathogenesis as a basis for vaccine design* Planning vaccine trials* Introducing new vaccines into the healthcare system * Future challenges for vaccines and immunizations

1

GLOBAL BURDEN OF DISEASE

PART A. The Burden of Vaccine-Preventable Diseases

MAUREEN BIRMINGHAM^* and CLAUDIA STEIN^†, ^*Vaccine Assessment and Monitoring, Department of Vaccines and Biologicals, World Health Organization, 1211 Geneva 27, Switzerland; ^†Epidemiology and Burden of Disease, Global Programme on Evidence for Health Policy, World Health Organization, 1211Geneva 27, Switzerland

I. INTRODUCTION. THE GLOBAL BURDEN OF INFECTIOUS AND PARASITIC DISEASES

Despite major progress in microbiological research, infectious and parasitic diseases continue to be a significant burden of disease worldwide. Traditionally, these diseases were described using health data from routine surveillance systems or epidemiological studies. Such data sources are often incomplete or unreliable, and studies that investigate particular conditions are often found to exaggerate claims on mortality. The latter is largely a reflection of comorbidity, in which several coexisting pathologies contribute to and compete for the cause of death.

The Global Burden of Disease (GBD) study of 1990 addressed these problems and quantified the burden of over 100 major disease groups, including infectious diseases, by using a novel and single metric, the disability-adjusted life year (DALY). DALYs express the years of life lost to premature death (YLL) and the years lived with disability (YLD) for varying degrees of severity, making time itself the common metric for death and disability [1]. One DALY is, therefore, a health gap measure, equaling 1 year of healthy life lost. Moreover, DALYs are internally consistent and disaggregate comorbidity, hence decoupling epidemiological measures from advocacy.

The GBD study estimated that, in 1990, over 31% of DALYs worldwide were due to communicable diseases (Table 1) [1, 2]. The vast majority of those occurred in developing countries, where 35% of DALYs were lost to infectious and parasitic diseases, whereas only a little over 4% of the burden in developed regions could be attributed to these disorders. The past 50 years have seen a dramatic decline in the burden of communicable diseases in established market economies, largely as a result of increased income and education and technological advances in sanitation, antimicrobials, and vaccines. It was, therefore, predicted that the burden of infectious diseases may decrease in less developed regions as their incomes rise and access to technological progress improves.

TABLE 1

Global Burden of Disease in 1990 and 2000

^aDALYs, disability-adjusted life years.

^bIncludes respiratory infections.

Although progress has been made with respect to some infectious diseases, including respiratory infections, diarrheal diseases, and measles (Table 1), the overall picture has changed little a decade later. Infectious and parasitic diseases still account for nearly 30% of the global burden in the year 2000 (Table 1) and for nearly 32% of the burden in developing countries [2]. Among the top ten leading causes of DALYs worldwide in the year 2000, five were infectious diseases: lower respiratory infections (the number one cause), HIV–AIDS, diarrheal diseases, malaria, and tuberculosis. The situation is particularly bleak in Africa, where 60% of the burden is caused by infectious and parasitic diseases [2]. The surge of the HIV–AIDS epidemic, which is currently causing 6.1% of the total burden and 5.3% of all deaths worldwide, is the major factor responsible for this discouraging score [2]. It largely explains why 26% of all deaths worldwide are still caused by communicable diseases, compared to 27% in 1990.

Whereas the number and rates of death from some communicable diseases, including measles, tuberculosis, and diarrheal diseases, have fallen over the past 10 years, others such as malaria and HIV have increased, particularly in developing countries [2]. This has been accompanied by a worldwide increase in the proportion of DALYs due to noncommunicable diseases from 36% in 1990 to nearly 40% in 2000. Developing countries therefore are experiencing a “double burden” from both communicable and noncommunicable diseases [2]. Given the enormous scope of vaccine technology in combating infectious diseases, efforts to improve access to these resources must therefore remain a major priority in health policy. The analysis of the global burden of infectious disease over the past decade shows that public health interventions against communicable diseases have seen both triumphs and setbacks; it is the purpose of this article to take the reader through past achievements and future opportunities in vaccinology,

II. BRIEF HISTORICAL PERSPECTIVE OF VACCINOLOGY

Vaccination, or the practice of artificially inducing immunity, has been and continues to be one of the most important public health interventions in history, The practice of vaccination can be traced to as early as the seventh century when Indian Buddhists drank snake venom to induce immunity, possibly through a toxoid-like effect [3]. Variolation against smallpox probably began early in the second millenium in central Asia and then spread east to China and west to Turkey [4]. Lady Mary Wortley Montagu introduced variolation into England during 1721 after observing the practice in Constantinople. By using local knowledge regarding the protective effects of cowpox and experimenting further with it, in 1798 Edward Jenner introduced the notion of large-scale, systematic immunization against smallpox by person-to-person inoculation with cowpox virus [4].

The field of vaccinology experienced its next major advance in the 1800s with the concepts of attenuation and virulence. The concept of “passage” of the immunizing agent between animals or humans was recognized as important to maintain its “strength.” In 1885, Louis Pasteur developed the first human vaccine against rabies [5]. In 1886, the concept of killed vaccine was developed when Salmon and Smith produced a killed hog cholera vaccine [6, 7]. This led to three new killed vaccines for humans: against cholera and typhoid in 1896 and against plague in 1897 [4]. Thus, by the end of the nineteenth century, two live attenuated viral vaccines (rabies and smallpox) and three killed bacterial vaccines (typhoid, plague, and cholera) were available for humans.

In the early twentieth century, toxoids were developed against diphtheria and tetanus [8–10], and by 1927, bacille Calmette–Guerin (BCG) vaccine was also available [11]. The isolation of the yellow fever virus in 1927 led to the French strain yellow fever vaccine, followed by the 17D strain, which had fewer side effects [4]. By 1936, two killed influenza vaccines were developed, followed by a live one in 1937. Vaccines against rickettsia ensued, in particular against Q–fever and typhus, the latter in heavy demand during World War II [11]. The first trials for pertussis vaccine, conducted in 1923 and 1924 on the Faroe Islands, led to the availability of several whole cell pertussis vaccines of varying efficacy by the 1940s [12, 13].

The advent of tissue culture in the 1940s sparked the next flurry of vaccine development, allowing for large-scale vaccine production [11]. This new technique made it possible for Enders, Robbins, and Weller to grow poliovirus in tissue culture, winning a Nobel prize for their achievements and leading to the licensure of the Salk and Sabin polio vaccines in 1955 and 1960, respectively [14]. During the 1960s, measles and mumps vaccines were licensed as well as the Japanese encephalitis vaccine, followed by the licensure of rubella and varicella vaccines in the 1970s [4]. The availability of many new vaccines created enormous potential to control several lethal diseases.

III. THE SMALLPOX ERADICATION ERA

Smallpox, one of the deadliest scourges known to humans, was prevalent throughout the world by the seventeenth century. The disease had a profound impact on history, wiping out large populations where it was introduced. It decimated Native American populations and contributed to the demise of the Inca and Aztec empires. In Europe alone, approximately 400,000 persons died annually from smallpox by the end of the eighteenth century [15]. The disease was endemic in populations large enough to sustain transmission, with periodic epidemics every 4–7 years [16]. In smaller or more isolated populations, the disease tended to “burn out,” but would resurge when the virus was reintroduced among enough susceptibles to sustain transmission. By using the cowpox-derived vaccine, smallpox transmission was greatly reduced in Europe after World War ...