S Sugaroon, V Wiwanitkit
S Sugaroon, V Wiwanitkit. Hepatitis A Vaccination: Is It Necessary For Thai Adults?. The Internet Journal of Asthma, Allergy and Immunology. 2004 Volume 3 Number 2.
Hepatitis A has been recognized as a growing child health problem within the last decade. This disease is easily transmitted via the fecal-oral route and from person-to- person. In some cases hepatitis A may also be spread through contaminated water and food. This acute illness has a sudden onset with fever, malaise, jaundice, anorexia, and nausea being the most common clinical manifestations. In infants and preschool children, however, infection may occur without the presence of jaundice, and mild nonspecific symptoms may be the only manifestation. Children may easily spread the infection to household adults who demonstrate more serious clinical manifestations and subsequent liver disease (Cuthbert , 2001; Kemmer and Miskovsky, 2000). Chronic infection as a result of hepatitis A is very unusual and fulminant cases of infection are rare unless the individual also has hepatitis B. According to the 15 th edition of Harrison's textbook of Internal Medicine, the mortality of hepatitis A infection is less than 0.1% or 1/1,000 or so. In the U.S. there are about 100 deaths resulting from hepatitis A per year.
This infection is a common infectious disease in the tropical countries including Thailand (Kosuwan
Materials and methods
This study was performed as a cost effectiveness analysis of several alternative strategies for vaccinating Thai adults towards hepatitis A infection. We focused the adult group (age 18 years old and above) because there have never been cost effectiveness analysis for this population in Thailand.
According to our study, a crucial factor in choice of a strategy for hepatitis A vaccination is consideration of the likely costs and benefits of various alternatives. Concerning the benefit, the most benefit is set as the least expensive. The tested strategies in this study were 1) no intervention, 2) vaccination without screening and 3) vaccination after screening. The hepatitis A vaccine mentioned in this study is the inactivated type, which present high immunogenicity at the range 98 - 100 % (Lopoez
Cost identification for each alternative strategy
At first the cost identification for investment of each alternative strategy was performed. According to our study, the costs were estimation in baht (42 baht = 1 USdollar). We used the primary data from the Financial Unit, King Chulalongkorn Hospital in our cost identification study. Only the direct cost involving in each alternative strategy (cost of hepatitis A screening test and cost of hepatitis A vaccine) was used in our cost identification.
Concerning the first strategy, no intervention, the cost identification for investment gave the cost equal to 0 baht. Concerning the second strategy, vaccination without screening, the cost identification for investment gave the cost equal to 1,430 baht (derived from the cost of one dosage of hepatitis A vaccine = 1,430). Concerning the third strategy, vaccination after screening, the cost identification for investment gave the cost equal to 1,710 baht (derived from the cost of two dosage of hepatitis A vaccine plus cost of hepatitis A screening test = 1,430 + 280).
Determination for the effectiveness of each strategy
The effectiveness in this study is the difference between the investment cost and the expected lost for each alternative strategy. Epidemiology data relating to the outcome of each alternative strategy (prevalence of natural immunity, immunogenicity of vaccine, prevalence of infection in susceptible group and outcome of infection) used in estimation of the expected lost for each alternative strategy were presented in Table 1 (Linglof T
The hepatitis A virus (HAV), a picornavirus, is a common cause of hepatitis worldwide. Hepatitis A remains an important cause of community-acquired hepatitis in the United States and in the world. Spread of infection is generally person to person or by oral intake after fecal contamination of skin or mucous membranes; less commonly, there is fecal contamination of food or water. Hepatitis A is endemic in developing countries, and most residents are exposed in childhood. In contrast, the adult population in developed countries demonstrates falling rates of exposure with improvements in hygiene and sanitation (Cuthbert , 2001; Kemmer and Miskovsky, 2000).
After ingestion and uptake from the gastrointestinal tract, the virus replicates in the liver and is excreted into the bile. Cellular immune responses to the virus lead to destruction of infected hepatocytes with consequent development of symptoms and signs of disease. Acute hepatitis A infection is clinically indistinguishable from other causes of acute viral hepatitis. In young children the disease is often asymptomatic, whereas in older children, children and adults there may be a range of clinical manifestations from mild, an icteric infection to fulminant hepatic failure (Willner
Furthermore, acute infection can be prevented with inactivated, highly immunogenic vaccines.
Challenges for the future include strategies for broad-based population vaccination, including cost-effective approaches. The recommendations for hepatitis A vaccination are different due to the settings. Some indicated the effectiveness of the alternative “vaccination after screening” (Chodick
In Thailand, hepatitis A infection is still an important viral infectious disease due to the poor sanitation in some area. A recent study indicated that up to 97.0 % of the Thai adults had natural immunity to this disease (Burke
Of interest, our results indicated that it is not cost effective to give the hepatitis A vaccination to the Thai adults at present. This trend is similar to the previous study among the Thai adolescents (Wiwanitkit
Department of Clinical Microscopy, Faculty of Allied Health Science,
Chulalongkorn University, Bangkok 10330 Thailand