The Contribution of Vaccination to Global Health Essay
The Contribution of Vaccination to Global Health Essay
For many centuries, smallpox devastated mankind. In modern times we do not have to worry about it thanks to the remarkable work of Edward Jenner and later developments from his endeavors. With the rapid pace of vaccine development in recent decades, the historic origins of immunization are often forgotten.
Pros and cons to Edward Jenner and the History of Smallpox and Vaccination Essay
Vaccination has made an enormous contribution to global health. Two major infections, smallpox and rinderpest, have been eradicated. Global coverage of vaccination against many important infectious diseases of childhood has been enhanced dramatically since the creation of WHO’s Expanded Programme of Immunization in 1974 and of the Global Alliance for Vaccination and Immunization in 2000. The Contribution of Vaccination to Global Health Essay. Polio has almost been eradicated and success in controlling measles makes this infection another potential target for eradication. Despite these successes, approximately 6.6 million children still die each year and about a half of these deaths are caused by infections, including pneumonia and diarrhoea, which could be prevented by vaccination. Enhanced deployment of recently developed pneumococcal conjugate and rotavirus vaccines should, therefore, result in a further decline in childhood mortality. Development of vaccines against more complex infections, such as malaria, tuberculosis and HIV, has been challenging and achievements so far have been modest. Final success against these infections may require combination vaccinations, each component stimulating a different arm of the immune system.
Citations about essay on Disease, Religion and Medicine: Smallpox in Nineteenth-Century Benin
Putative vaccine safety issues are commonly reported while reviews of vaccine benefits are few. A Medline search over the past five years using the keywords “vaccine risks” scored approximately five times as many hits (2655 versus 557) as a Medline search using “vaccine benefits” as keywords. (Atkinson P, Cullinan C, 2005) This reflects the fact that negative aspects of vaccination get much more publicity than positive aspects. How one addresses the antivaccine movement has been a problem since the time of Jenner. The best way in the long term is to refute wrong allegations at the earliest opportunity by providing scientifically valid data. This is easier said than done, because the adversary in this game plays according to rules that are not generally those of science. The Contribution of Vaccination to Global Health Essay. This issue will not be further addressed in this paper, which aims to show how vaccines are valuable to both individuals and societies, to present validated facts, and to help redress adverse perceptions. Without doubt, vaccines are among the most efficient tools for promoting individual and public health and deserve better press. (Andre FE, 2005)
Conclusion to Vaccination Resistance in Historical Perspective Essay
Briefly, a national program of traditional pharmacopoeia and medicine has been established within the Ministry of Health. The findings of research sponsored by the program shed light on nineteenth-century narrative accounts of prevalent diseases and indigenous healing techniques. They also provide a comparative historical background for early colonial health policy and the current particular interest in the curative potential of traditional medicine. The Contribution of Vaccination to Global Health Essay.
References
Folb PI, Bernastowska E, Chen R, Clemens J, Dodoo AN, Ellenberg SS, et al. A global perspective on vaccine safety and public health: the Global Advisory Committee on Vaccine Safety. Am J Public Health 2004; 94: 1926-31.
Atkinson P, Cullinan C, Jones J, Fraser G, Maguire H. Large outbreak of measles in London: reversal of health inequalities. Arch Dis Child 2005; 90: 424-5.
Andre FE. What can be done to make vaccines more trendy? Expert Rev Vaccines 2005; 4: 23-5.
Henderson DA. Lessons from the eradication campaigns. Vaccine 1999; 17: S53-5.
Fine PE, Griffiths UK. Global poliomyelitis eradication: status and implications. Lancet 2007; 369: 1321-2. The Contribution of Vaccination to Global Health Essay.
Vaccination has made an enormous contribution to global health. Two major infections, smallpox and rinderpest, have been eradicated. Global coverage of vaccination against many important infectious diseases of childhood has been enhanced dramatically since the creation of WHO’s Expanded Programme of Immunization in 1974 and of the Global Alliance for Vaccination and Immunization in 2000. Polio has almost been eradicated and success in controlling measles makes this infection another potential target for eradication. Despite these successes, approximately 6.6 million children still die each year and about a half of these deaths are caused by infections, including pneumonia and diarrhoea, which could be prevented by vaccination. Enhanced deployment of recently developed pneumococcal conjugate and rotavirus vaccines should, therefore, result in a further decline in childhood mortality. The Contribution of Vaccination to Global Health Essay. Development of vaccines against more complex infections, such as malaria, tuberculosis and HIV, has been challenging and achievements so far have been modest. Final success against these infections may require combination vaccinations, each component stimulating a different arm of the immune system. In the longer term, vaccines are likely to be used to prevent or modulate the course of some non-infectious diseases. Progress has already been made with therapeutic cancer vaccines and future potential targets include addiction, diabetes, hypertension and Alzheimer’s disease.
It is often stated that vaccination has made the greatest contribution to global health of any human intervention apart from the introduction of clean water and sanitation, but this is a claim that needs some qualification. Study of the pattern of infectious diseases in industrialized countries from the end of the nineteenth century onwards shows that there was a large and progressive decline in child mortality, owing largely to a reduction in mortality from infectious diseases, prior to the development and deployment of vaccines. This was associated with improvements in housing, nutrition and sanitation. Nevertheless, it is indisputable that vaccination has made an enormous contribution to human and animal health, especially in the developing world. Mortality from smallpox and measles was massive in the pre-vaccination period with up to a half of the population dying from the former during epidemics and measles was only a little less lethal in susceptible populations.
This review describes briefly some of the major past achievements of vaccination, the present situation in relation to the global use of vaccines and some of the ways in which vaccination could contribute to global health in the future.
2. PAST CONTRIBUTION OF VACCINATION TO GLOBAL HEALTH
(a) Jenner and the eradication of smallpox
The development of vaccination as a public health tool is attributed to Edward Jenner and his experiments with coxpox in 1796 (figure 1), although the practice of variolation using ‘wild’ smallpox virus had been practiced in some countries for much longer [1]. Variolation worked but carried a significant risk of severe disease or even death in the recipient. The Contribution of Vaccination to Global Health Essay. This risk was reduced dramatically by substituting smallpox material by fluid from a cowpox lesion. The cowpox virus causes only mild infections in humans but induces an immune response which provides cross-protection against smallpox infection, the principle that has underpinned the development of all subsequent vaccines based on an attenuated organism. Vaccination was adopted as a public health tool relatively rapidly in Europe and the USA, although not without fierce opposition from some sections of the community, especially when vaccination was made compulsory as was the case in the UK following the introduction of the Vaccination Act in 1871 [2]. The anti-vaccination campaign, which continues today in both industrialized and developing countries, had some surprising supporters including Alfred Russel Wallace, co-discoverer of evolution [3].
Edward Jenner by John Raphael Smith (Wellcome Library).
As smallpox vaccine was the first vaccine to be deployed widely in man, it was appropriate that smallpox was the first human infectious disease to be eradicated by vaccination, a milestone achieved in 1979. The story of the eradication of smallpox is described by Henderson, who played a key role in the eradication campaign, in his book ‘Smallpox—the eradication of a disease’, which sets out the challenges that the eradication team faced and how these were met: important lessons for today [4]. The key to the final stages of the campaign was intensive surveillance for cases and a focal response following detection of a case. Smallpox had a number of advantages as a target for eradication. Firstly, the disease has distinctive clinical features; secondly, it was well recognized and much feared in the communities where it was prevalent; and finally, and perhaps most importantly, sub-clinical infections were rare. Measles, another potential candidate for eradication, has some of these features, and local transmission of measles virus has already been interrupted in the Americas. However, polio virus, unlike smallpox and measles viruses, usually causes a hidden, asymptomatic infection, making eradication of this infection especially challenging (see below).
Smallpox is the only human infection to have been eradicated, although eradication of guineaworm infection is close. Eradication of the rinderpest virus, formally recognized by the World Health Organization in 2011, is less widely recognized than eradication of smallpox, but this represents another major milestone in the control of infectious diseases and has been a major contribution to global health [5,6]. The Contribution of Vaccination to Global Health Essay. Rinderpest, closely related to measles and distemper viruses, can cause high mortality in cattle, impoverishing families in developing countries dependent upon their cattle and making them susceptible to malnutrition and many infectious diseases. Recently, there has been closer interaction between research groups developing human and veterinary vaccines through organizations such as the Jenner Vaccine Institute (www.jenner.ac.uk (accessed 8 November 2013)), a development to be encouraged as common technologies can be applied in each area and some vaccines, for example a tuberculosis vaccine, could be used in man and his domestic animals.
(b) The next generation of vaccines
The next human vaccine to be developed using the principle of attenuation was rabies vaccine, developed by Pasteur and first tested in man in 1885, nearly a century after Jenner’s experiments [7]. This vaccine was based on material obtained from infected rabbit brain attenuated by drying, an uncertain process, and vaccines prepared in this way frequently caused serious side effects. Most human rabies vaccines are now based on inactivated virus grown in tissue culture [8]. The Contribution of Vaccination to Global Health Essay. Acquisition of the ability to grow viruses in tissue culture for an extended period led to the development of attenuated vaccines against measles and poliomyelitis in the 1950s and the 1960s [9]. Subsequently, many other vaccines have been developed using the principle of attenuation, including rubella, influenza, rotavirus, tuberculosis and typhoid vaccines. Vaccines based on attenuated organisms generally induce a strong and sustained immune response, induce more effective immunity at mucosal surfaces than killed vaccines and are usually relatively easy and cheap to make. Because the vaccine components are alive, they can spread to non-vaccinated subjects, extending the impact of vaccination to the community at large (table 1). However, because these vaccines are alive, mutations may occur in the attenuated vaccine strain with a reversion to virulence, as seen rarely with oral polio vaccine which causes paralysis in about one in two million recipients, and they may cause significant illness in subjects with impaired immunity, as has been seen with the anti-tuberculosis vaccine bacille Calmette Guérin (BCG) when given to immunodeficient patients, including those with human immunodeficiency virus (HIV) infection [10]. The Contribution of Vaccination to Global Health Essay.
Table 1.
Advantages and disadvantages of attenuated and killed vaccines.
| characteristic | attenuated vaccine | killed vaccine |
|---|---|---|
| thermostability | usually low | usually high |
| reactogenicity | usually low | frequently high |
| immunogenicity | usually long-lasting | often short duration |
| mucosal immunity | often strong | variable |
| safety | reversion to virulence may occur may cause serious infections in immunocompromised | safety high |
| indirect herd protection | may infect and protect non-vaccinated | can protect non-vaccinated by interrupting transmission |
An alternative way of making microorganisms safe for use in a vaccine is to kill them, and at the beginning of the twentieth century a number of vaccines based on killed whole organisms, including the pneumococcus, meningococcus and typhoid bacillus, were developed and used. These vaccines were usually poorly immunogenic and often caused significant side effects (table 1), so that whole-cell vaccines have largely given way to subunit vaccines. However, there has recently been a renewed interest in use of whole-cell vaccines, which have the advantage of presenting multiple antigens, and whole-cell, attenuated pneumococcal [11] and malaria [12,13] vaccines have recently been developed and are being evaluated in clinical trials. The symptoms and signs of tetanus and diphtheria are caused by soluble toxins produced by the causative bacteria, and at the beginning of the twentieth century anti-toxins were developed to treat and prevent these infections with some success. However, the prevention provided by anti-toxins was only short lived, and in the 1920s it was shown that sustained protection against these infections could be achieved by immunization with a modified toxin (toxoid); these straightforward and safe vaccines are still being used widely today. The Contribution of Vaccination to Global Health Essay. Tetanus toxoid, diphtheria toxoid and a killed pertussis (whooping cough) vaccine (DPT) was developed in 1931 and remains a key component of infant immunization programmes across the world. In many countries, the original whole-cell pertussis component of DPT has been replaced with a less reactogenic, acellular pertussis component, and DPT is now used widely in combination with hepatitis B and Haemophilus influenzae type b (Hib) vaccines, a combination widely known as pentavalent vaccine or ‘penta’.
By the late 1950s, the majority of children in developed countries were receiving routine vaccination with DPT and polio vaccines and, in some countries, vaccination against tuberculosis. Consequently, the incidence of these infections as important public health problems declined substantially, although in the case of pertussis and measles, success has not been complete as outbreaks of these infections still occur in industrialized countries, including the UK, owing to periodic declines in vaccine coverage. These declines in coverage are often a consequence of the activities of an active anti-vaccination lobby, as was the case in the UK following the spurious reports of a link between autism and a combined measles, mumps and rubella vaccine [14]. The measles virus has a high reproductive potential, and a high, sustained level of vaccine coverage is required to interrupt transmission.
(c) The expanded programme on immunization
By the 1960s, the vast majority of deaths and severe illnesses attributable to the common infectious diseases of childhood preventable by vaccination were occurring in children in the developing world, where coverage with vaccines such as measles was frequently less than 5% and restricted largely to children of the small, wealthy section of the community, the group at least risk of a serious outcome from an infection such as measles. At this time, the early 1960s, about one-third of African children did not reach the age of 5 years and infectious diseases, particularly measles, accounted for a substantial proportion of these deaths. The Contribution of Vaccination to Global Health Essay. In the face of this challenge, the World Health Organisation (WHO) established the Expanded Programme on Vaccination (EPI) in 1974 to increase the uptake of routine childhood vaccines across the world. This programme has been very successful, with coverage rates of EPI vaccines climbing rapidly from less than 5% to over 80% in many low and low middle-income countries [15]. By the 1980s, coverage with EPI vaccines in many low-income counties was similar to, or even better than, that achieved in many parts of the industrialized world where the infectious diseases of childhood were no longer seen as a significant threat.
The success of the EPI programme was achieved in part because of sound leadership in WHO and in many developing countries, and in part through financial support from the international community. Because EPI vaccines are relatively cheap when mass produced, full immunization of a child cost around $15 in the 1990s. Introduction of effective national EPI programmes in most developing countries has led to major reductions in deaths and hospital admissions from measles and neonatal tetanus. It has been estimated that in 2012 there were about 157 000 deaths from measles (www.who.int/topics/measles (accessed 8 November 2013)), a dramatic decrease from the situation 20 years ago (figure 2) but still an unacceptable burden from a preventable infection. There has also been a dramatic reduction in the number of deaths from neonatal tetanus (over 90% since the 1980s), achieved through routine immunization of mothers attending antenatal clinics with tetanus toxoid, but it is estimated that there were still about 60 000 preventable deaths from this infection in 2012 (www.who.int/topics/tetanus (accessed 8 November 2013)). The impact of vaccination has not been limited to the developing world, and a recent review from the USA [16] estimated that 103 million cases of selected infectious diseases had been prevented by vaccination since 1924. The Contribution of Vaccination to Global Health Essay.
