The Introduction of the New Dengue Vaccine in Thailand - Term Paper Example

Individual Report Introduction Dengue Fever is an infectious and endemic disease commonly found in tropical regions and is essentially transmitted by the dengue virus1. Some of the symptoms associated with this disease include severe fever, headaches, and joint and muscle pains2. Dengue Haemorrhagic Fever (DHF) is the severe form of the fever that is life threatening and is often characterised by abdominal pain, bleeding, black stool, vomiting and restlessness. To date, there are no specific treatments for both forms of Dengue Fever3. However, much effort has been directed towards developing a vaccine that will avert or minimise the outbreak or transmission of the fever. There are several vaccine candidates at different stages of development; nevertheless, the most promising of these vaccines is one that was developed by the company Sanofi Pasteur. Clinical trials in phase two have found this vaccine to be very immunogenic. Currently, this vaccine is on its phase three trials and is likely to be approved and included in the national immunisation programs in various countries around the world after it has gone through comprehensive clinical trials 4. The main aim of this report is to explore some of the key factors that revolve around the introduction of the new Dengue vaccine in Thailand. Firstly, this report will examine some of the main factors that have determined the introduction of the vaccine in Thailand’s immunisation programs. In this case, the factors that will be discussed include the disease burden and surveillance of Dengue Fever in Thailand and the efficacy and safety of the Dengue vaccine. Secondly, this report will discuss some of the major benefits and challenges of introducing the vaccine in Thailand. In addition, based on the key issues highlighted, this report will present arguments against the introduction of the vaccine in Thailand’s national immunisation program. Disease Burden Based on WHO guidelines on vaccine introduction, disease burden is among the key policy issues that determine whether or not a new vaccine can be included into a national health immunisation program. Basically, disease burden gives an evidentiary justification for forming national health priorities and is expressed through hospitalisation cases, prevalence rates, mortality rates and cases of long-term disability. The higher the disease burden expressed in the above factors, the greater the priority assigned to a particular disease in the national health policy5. According to Endy, Clark, Nisalak, Mammen and Puthimethee (2005), Dengue Fever and Dengue Haemorrhagic Fever is a significant disease burden in Thailand6. The fever was first reported in 1949 in Bangkok but the first epidemic occurred in 1958. Since then, cases of Dengue Fever in Thailand have varied from year to year. It is estimated that from 1983 to 1997 there were approximately 850,000 cases of infections in Thailand7. When assessing the yearly cases of morbidity per 100,000 people it is evident that Dengue Fever morbidity incidences in Thailand have fluctuated and increased with time. In 1958 the morbidity incident was at 8.9/100,000 but by 2006 it had further increased to 74.8/100,000. Nonetheless, the highest morbidity incidences occurred in 1987 when it was estimated that they were at 325/100,000. It was during this year that the highest mortality rates as a result of Dengue Fever were reported7. In recent years, there have been many reported incidences and death cases related with Dengue Fever in Thailand. For instance, the Southern Epidemiology Department reported that between 2000-2004 there were over 113,591 cases of infection and 251 deaths linked to the fever infection in the Southern part of Thailand. In 2002, cases of the fever were especially high in Southern Thailand where there were over 33,617 reported cases of infection and 64 deaths. Similarly, in 2005, cases of the fever were also high and there were 2992 reported cases of infection and 5 deaths. Since 2005, there have been substantial reported cases of infections but fewer deaths8. The spread and transmission of Dengue Fever in Thailand is mainly associated with the rainy season, which occurs between March and September. A number of studies depict that Dengue Fever conveys inter and intra-annual variability, which comes as a result of extrinsic factors, such as climate variability, and intrinsic factors, such as host susceptibility and host-virus interactions9, 12. These factors may inevitably increase incidence rates of the fever10. Similarly, Cazelles (2005) notes that there is a positive correlation between Dengue Fever outbreaks and El Niño periods in Thailand.11 Disease Surveillance Disease surveillance is one of the important aspects of studies revolving around the national burden of disease since it provides data on the prevalence of the infections, hospitalisations, disabilities and mortalities that come as a result of a particular disease. Data on disease surveillance provides significant input or information that can be used for policy decision-making when it comes to the introduction of a vaccine5. In Thailand, Dengue Fever poses a considerable health risk to individuals as well as on the national healthcare systems. For instance, surveillance data from Thailand’s ministry of public health shows that, in 2008, there were 43,911 reported cases of Dengue Fever and 46 deaths13. In 2010, the total number of infection cases reported was 108,863 and the number of deaths was 131. Studies conducted to determine the economic costs of illness in terms of the quantity or value of resources used in the prevention, management and treatment of a certain disease show that Dengue Fever imposes social and economic stress on individuals, households, healthcare systems and society at large17. Although there is insufficient data showing the hospitalisation cases of Dengue Fever, it is estimated that 45% of infection cases have resulted in hospitalisation. In Thailand, Dengue Fever is the third major cause of hospitalisation cases amongst children15 and severe form of the fever often leads to long hospitalisation periods14. When the direct cost of hospitalisation and loss of productivity are accounted for, Endy, Clark and Nisalak et al. (2005) note that the Dengue Fever causes a financial loss of about $61 per affected household in Thailand. This amount is more than what many families in Thailand earn in a month6. Vaccine Efficacy and Safety This is also a key policy issue that is considered when introducing a new vaccine into a national health vaccine program. Basically, vaccine efficacy relates to the impact of the vaccine on measurable end points such as clinical disease phases and the biological markers that are considered during clinical trials. In some cases, a vaccine may have different effects on the persons vaccinated18. The vaccine can also minimise the susceptibility of the disease, slow down its progression, indirectly immunise the non-infected individuals5. Determining the efficacy of a vaccine is essential prior to incorporating a new vaccine into a national vaccine program since national health policies of countries such as Thailand often require particular standards for vaccine efficacy and safety before the vaccine is approved or authorised in the country’s national vaccine program. Before a new vaccine is approved and introduced in a country, it has to undergo comprehensive prevention, early detection, supportive care and diagnostic trials. These procedures could take up to 12 years since they are very costly, time consuming and involve a large number of human and animal subjects.18 To date, the Dengue vaccine developed by Sanofi Pasteur is in its the third phase of comprehensive clinical trials, which are geared towards evaluating the efficacy and safety of the vaccine. The first two phases of the clinical trials showed significant immunogenicity of the vaccine and no significant safety risks23. Nevertheless, these results were only established through testing children based in Latin America and Asia. Hence, the evaluation of the vaccine’s efficacy is yet to go through a large-scale testing that will establish comprehensive results4, 18. Challenges and Benefits of Introducing a Dengue Vaccine in Thailand Guy, Barrere and Malinowski et al. (2011) observe that establishing the safety, efficacy, quality and immunogenicity of a vaccine in order to adhere to the requirements of Thai health policies is one of the key challenges. In order for the vaccine to be approved and incorporated in Thai’s national vaccination program, the safety, efficacy and quality of the vaccine should be comprehensively determined. Currently, Sanofi Pasteur’s Dengue vaccine is still at phase three of the trial phase and has only been tested on Asian and Latin American populations. Hence, there is no definite or comprehensive clinical evidence on the efficacy or immunogenicity of the new vaccine4. Consequently, this is a major challenge, or indeed hindrance, for the introduction of the Dengue vaccine in Thailand due to the vaccine policies that dictate high standards of safety, efficacy, quality and immunogenicity5, 19. Moreover, based on the findings of various literature sources reviewed in this report regarding the disease burden of Dengue Fever in Thailand it is evident that, in as much as there are increasing reports of infection incidences, the death reports are significantly minimal. Compared to other diseases such as HIV/AIDS, Malaria and TB the effects or disease burden of Dengue Fever in Thailand is less19, 20. Hence, it may be difficult to justify why Dengue Fever should be given priority in the national health program particularly when it comes to funding. Furthermore, the lack of sufficient funding to support the inclusion or implementation of the Dengue vaccine in Thailand could be a major challenge. Given that Thailand’s economy is still in its developing phase, it may be difficult for the government to give priority to the implementation of the vaccine since there are other prevalent high risk diseases in Thailand such as HIV/AIDS, Malaria and TB, all of which require significant financial commitment from the Thai government19, 20, 24, 25. Nevertheless, I strongly recommend that the new Dengue vaccine should be introduced in Thailand. Based on the findings of various literature sources reviewed in this report regarding the disease burden of Dengue Fever in Thailand, it is evident that this fever is a potential health risk to a majority population in Thailand. According to Anderson, Chunsuttiwat and Nisalak et al. (2007) children are the population that are most vulnerable to this infection. It was reported that, in Thailand, Dengue Fever is the third major cause of hospitalisation cases amongst children 15. Dengue outbreaks have contributed to increased cases of infections and over 1000 deaths. Currently, there are no specific treatments for this fever and, as a result, much effort is directed towards prevention of the disease through vector control. Over time this strategy has proved to be somewhat ineffective since cases of Dengue Fever are on the rise in Thailand. Therefore, there is need for a vaccine to help combat this epidemic. A Dengue vaccine will help to prevent the outbreak or transmission of the infection. This will in turn help to prevent the fever from becoming a major disease burden in Thailand, especially during the rainy season. In addition, the administration of a Dengue vaccine will help to improve the immunogenicity of the population in Thailand, especially children, who are most vulnerable to this infection. This will help to minimise the financial health costs and loss of productivity that is associated with infection cases21, 22. Conclusion This report has explored some of the key factors that should be taken into account prior to introducing a new vaccine in Thailand. It has also examined the benefits and challenges associated with the launch of a Dengue vaccine. The findings of this report depict that Dengue Fever is a potential health risk to a majority of the Thai population. However, it is apparent from this report that, as compared to other diseases such as Malaria, the disease burden of Dengue Fever is less significant. It has also been established that the efficacy and safety of clinical trails of the Dengue vaccine are not definite or comprehensive. Consequently, the introduction of the vaccine in Thailand may experience a great many challenges with regards to vaccine policies, funding, feasibility of the program, efficacy and safety. Nevertheless, I strongly recommend that the new Dengue vaccine should be introduced in Thailand so as to prevent the outbreak and transmission of the fever and enhance the immunogenicity of the Thai population. Read More