Autism incidence up sharply in Thailand from 1998-2002
J Med Assoc Thai. 2005 Jul;88(7):891-7. Links
Trend study of autistic spectrum disorders at Queen Sirikit National Institute of Child Health.
Plubrukarn R,
Piyasil V,
Moungnoi P,
Tanprasert S,
Chutchawalitsakul V.
Child and Adolescent Psychiatry Department, Queen Sirikit National Institute of Child Health, Bangkok 10400, Thailand.
BACKGROUND: Increases in the incidence and prevalence of autistic spectrum disorders have been reported recently in the United States and Europe, but there are only a few reports on the trend of this problem in Thailand. OBJECTIVES: To study trend in autistic spectrum disorder patients and to find the factors that correlate with the incidence of this disorder at Queen Sirikit National Institute of Child Health. MATERIAL AND METHOD: A hospital-based prospective trend study was conducted in patients aged less than 12 years old, who attended the Child and Adolescent Department, Queen Sirikit National Institute of Child Health, Bangkok, form January 1998 to December 2002. Autistic spectrum disorders were defined as autistic disorder pervasive developmental disorder-not otherwise specified (PDD-NOS), and Asperger's disorder Related factors were recorded and analyzed Aged-adjusted incidence rate in both sexes and proportion rates of related factors were calculated by using the direct method Standard t-test and correlation coefficient were performed to test for statistically significant difference in the prevalence rate in each group. RESULTS: There were 610 new patients aged less than 12 years who displayed behavior consistent with autistic spectrum disorders. The increasing trend in the incidence of autistic spectrum disorder is observed (r = 0. 935, p = 0. 02). The incidence rate of autistic spectrum disorders among out patients less than 12 years has increased from 1.43 per 10, 000 in 1998 to 6.94 per 10, 000 in 2002. The correlation factors "an only one child in the family" is observed (r = 0.9, p = 0.038). CONCLUSION: During the 5 years of the study, a significant increase in the incidence of autistic spectrum disorders was observed at Queen Sirikit National Institute of Child Health. Increase in the incidence of ASD in this center cannot explain by any solid evidence from the present study.
PMID: 16241015 [PubMed - indexed for MEDLINE]
In 1992, Thailand began a universal hepatitis B vaccination program under WHO's EPI, or Extended Program of Immunization. I doubt they were injecting neonates with thimerosal-free hep B shots.
Volume: 27S3 • September 2001
Viral Hepatitis and Emerging Bloodborne Pathogens in Canada
http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/01vol27/27s3/27s3k_e.html
Hepatitis B and its Control in Southeast Asia and China Zhiyong Hong, Shimian Zou, Antonio Giulivi
Hepatitis B is one of the major infectious diseases of mankind: of 360 million chronic carriers worldwide, 78% are in Asia, 16% in Africa, 3% in South America, and 3% in Europe, North America, and Oceania combined. HBV infection is the most common cause of chronic hepatitis, liver cirrhosis and HCC worldwide(1).
In order to combat HBV infection and subsequent carriage, most East Asian and Southeast Asian countries introduced mass vaccination programs during the late 1980s and mid-1990s, which have resulted in a drastic decline in the HBV carrier rate and the number of patients with HCC.
Although HBV prevalence is low in Canada, changes in the epidemiology of this disease in other parts of the world may have a significant impact on the health of Canadians. Therefore, it is important to closely and continuously monitor the status of the disease in the world, especially in areas where HBV is endemic.
Indonesia The island of Lombok, east of Bali in Nusa Tenggara Barat Province, was the first to introduce a mass infant hepatitis B immunization project in Indonesia, which ran from November 1987 to October 1991(2). The Lombok Project clearly demonstrated the feasibility of incorporating HBV vaccine into the Expanded Program on Immunization (EPI) in a way that can significantly reduce chronic HBV infection and strengthen the EPI. The success of the Lombok Project was the basis for a national program of universal infant immunization in Indonesia. Four provinces were added to the program in 1991-1992, and the program was further expanded to 10 provinces in 1992-1993, requiring 4.5 million annual vaccine doses. The overall reduction in the prevalence of HBsAg among fully vaccinated children (less than 4 years old) fell from 6.2% to 1.9%, for a reduction of 70%.
Malaysia From February 1997 to July 1999, a total of 79,103 individuals, including university students, health care workers, and primary and secondary school students, participated in a prospective study of hepatitis B. In all, 92.9% were Chinese, 4.8% were Malays, 2.1% were Indians, and 0.1% were from other ethnic groups(3). The age of the participants ranged from 5 to 60 years old. Demographic data and history of hepatitis B vaccination were obtained from each participant, and testing was carried out for HBsAg and anti-HBs. The overall prevalence of HBsAg was 1.5%. The rate among the Malays, Chinese, and Indians was 1.5%, 1.5%, and 0.3% respectively. Among all participants, 62.4% had been vaccinated with all three doses of HBV. Chinese participants were found to have the highest vaccination rate (64.5%), followed by Indians (37.8%), and Malays (32.7%). The rate of endemic HBV in Malaysia is now low, as its vaccination programs and possibly other intervention measures have successfully reduced the incidence of the infection(4).
The Philippines The prevalence of chronic HBV infection in the Philippines, as indicated by HBsAg positivity, has been found to range from 2.0% to 16.5%, with an average of 12.0%, in a study of rural villagers(5). In a study assessing the feasibility and effectiveness of incorporating hepatitis B vaccine into the national EPI, HBsAg positivity decreased to 2% during the last 10-year period (1987-1996) in the Philippines(6).
The Republic of Singapore In Singapore, the HBsAg carrier rate for the general population was 9% to 10% in 1980-1981. A national childhood hepatitis B vaccination program was formulated and implemented in phases, starting with babies born to carrier mothers on October 1, 1985, and finally extending to all newborns on September 1, 1987. During the period from 1994 to 1996, more than 90% of children completed the full schedule of immunization by 1 year of age, and 85% had evidence of vaccination at school entry at age 6. Follow-up of two cohorts of vaccinated children showed that perinatal transmission was reduced by 80% to 100%. Horizontal transmission also declined through other public health measures. The incidence of acute hepatitis B declined from 10.4 per 100,000 in 1985 to 4.8 per 100,000 in 1996(7). The vaccination coverage in newborns reached 100%, and the HBsAg positive rate declined to 2% to 3% in 1997 and 1998 in randomized population groups and in new blood donors. The acute HBV morbidity had fallen continuously from 10.4 per 100,000 in 1985 to 4.5 per 100,000 in 1997, and the incidence of HCC continued to decline(8).
Thailand In 1992, hepatitis B vaccine was included in the EPI on a nationwide scale in Thailand. Recent data on the immunization program against hepatitis B demonstrate a steady decline in the incidence of HBV carriers among the Thai population during the period from 1981 to 1991. For example, the prevalence of HBV carriers among blood donors and students decreased from 8.2% and 6.6 % in 1987 to 6.5% and 5.2% in 1991 respectively(9). Current data from an epidemiologic survey in Songkhle Province in the south of Thailand demonstrated an overall prevalence of HBV carriers of 0.55% among children less than 15 years of age(10). It has been clearly shown that hepatitis B immunization as part of the EPI is highly efficient in protecting newborns from infection.
Viet Nam Blood donors from two cities in Viet Nam were tested for markers of HCV and HBV infection. Among 491 donors in Ho Chi Minh City and 499 donors in Hanoi City, HBsAg carrier rates were 3.1% and 3.0% respectively(11). There is no report about the HBsAg carrier rate in the general population.
China (mainland) HBV infection rates reported for university students ranged from 4.5% to 19.4% during the period from the mid-1980s to the early 1990s(12). The HBsAg carrier rate in China showed a substantial decrease after the implementation of the WHO strategy. Zeng et al carried out a randomized two-stage household sampling survey at 112 disease surveillance points from 25 provinces, autonomous regions, and municipalities of China in 1996(13). The results showed that the hepatitis B vaccination coverage rates among neonates were 96.7% in 1993 and 97.5% in 1994-1996 in urban areas, and 50.8% in 1993 and 73.9% in 1994-1996 in rural areas. Vaccination coverage rates among 7-9 year-old students in 1994 in urban and rural areas were 97.5% and 73.9% respectively. Lu et al conducted a sampled survey on hepatitis A, B, and C in Yunnan province, China, in 1998(14). The prevalence of HBsAg was 2.0% in 452 serum samples collected from pupils aged 6-12 years old in three different counties. Zhang et al(15) determined the persistence of immunity in neonates born to HbsAg positive mothers following HB immunization with different schedules(15). In total, 203 neonates were followed-up continuously for 6 years for anti-HBs and HBsAg. Anti-HBs in the neonates was maintained in greater than 90% of the children during those years. None of the children tested positive for HBsAg. A booster dose of vaccine after the primary immunization seemed unnecessary for children 6-10 years old. Zhu et al(16) reported the results of the status of hepatitis B vaccination in China from the 1999 National Coverage Study. A total of 25,878 children aged 18-34 months from 31 provinces were surveyed. The national hepatitis B vaccine coverage (receipt of three doses) was 70.7%.
Hong Kong A campaign to promote screening and vaccination for hepatitis B in students at the University of Hong Kong was described by Marshall (1995)(17). Of eligible students, 98% had the first dose of vaccine, and greater than 96% completed the full course of three doses. After vaccination, the prevalence of HBsAg was 3.6%; male students showed a significantly higher prevalence (4.5%) than female students (2.9%). These levels are about one-third of the prevalence levels found in the same age group in the general population in Hong Kong. The author recommended that students at secondary schools and post-secondary educational institutions in Hong Kong should be offered serologic screening and vaccination for hepatitis B.
Taiwan In the early 1980s, 15% to 20% of the population of Taiwan were estimated to be HBV carriers. A program of mass vaccination against hepatitis B was launched in 1984. In the first 2 years of the program, newborns of all HbsAg positive mothers were vaccinated. Since 1986, all newborns, and then pre-school children, primary school children, adolescents, young adults, and others have also been vaccinated. Vaccination coverage was greater than 90% for newborns, 79% of pregnant women being screened for HBsAg. The proportion of babies who were born to highly infectious carrier mothers and became carriers decreased from 86% to 96% to 12% to 14%, whereas the decrease was from 10% to 12% to 3% to 4% for babies of less infectious mothers. Between 1989 and 1993, the prevalence of HBsAg among children aged 6 years also fell, from 10.5% to 1.7%. The average annual incidence of HCC among children aged 6-14 years decreased significantly, from 0.7/100,000 in 1981-1986 to 0.4/100,000 in 1990-1994. Similarly, the annual incidence of HCC among children aged 6-9 years declined from 0.5/100,000 for those born in 1974-1984 to 0.1/100,000 for those born in 1986-1988. These data demonstrate that the mass vaccination program has been effective in controlling chronic HBV infection and in preventing liver cancer in Taiwan. If a 90% coverage rate of hepatitis B vaccination in newborns can be maintained, the carrier rate of HBsAg in Taiwan is expected to decline to lower than 0.1% by year 2010(18).
Summary The most recent data from Southeast Asia and China show that there have been substantial decreases in the incidence and prevalence of hepatitis B following the immunization strategies that have been implemented in that region. However, it should also be noted that the overall HBV prevalence rate is nevertheless high in the area, especially among children and adults born before the introduction of the current hepatitis B vaccination programs. Both aspects of the epidemic pattern in that area may have implications for decision making regarding the prevention and control of hepatitis B in Canada.
References
J Med Assoc Thai. 2005 Jul;88(7):891-7. Links
Trend study of autistic spectrum disorders at Queen Sirikit National Institute of Child Health.
Plubrukarn R,
Piyasil V,
Moungnoi P,
Tanprasert S,
Chutchawalitsakul V.
Child and Adolescent Psychiatry Department, Queen Sirikit National Institute of Child Health, Bangkok 10400, Thailand.
BACKGROUND: Increases in the incidence and prevalence of autistic spectrum disorders have been reported recently in the United States and Europe, but there are only a few reports on the trend of this problem in Thailand. OBJECTIVES: To study trend in autistic spectrum disorder patients and to find the factors that correlate with the incidence of this disorder at Queen Sirikit National Institute of Child Health. MATERIAL AND METHOD: A hospital-based prospective trend study was conducted in patients aged less than 12 years old, who attended the Child and Adolescent Department, Queen Sirikit National Institute of Child Health, Bangkok, form January 1998 to December 2002. Autistic spectrum disorders were defined as autistic disorder pervasive developmental disorder-not otherwise specified (PDD-NOS), and Asperger's disorder Related factors were recorded and analyzed Aged-adjusted incidence rate in both sexes and proportion rates of related factors were calculated by using the direct method Standard t-test and correlation coefficient were performed to test for statistically significant difference in the prevalence rate in each group. RESULTS: There were 610 new patients aged less than 12 years who displayed behavior consistent with autistic spectrum disorders. The increasing trend in the incidence of autistic spectrum disorder is observed (r = 0. 935, p = 0. 02). The incidence rate of autistic spectrum disorders among out patients less than 12 years has increased from 1.43 per 10, 000 in 1998 to 6.94 per 10, 000 in 2002. The correlation factors "an only one child in the family" is observed (r = 0.9, p = 0.038). CONCLUSION: During the 5 years of the study, a significant increase in the incidence of autistic spectrum disorders was observed at Queen Sirikit National Institute of Child Health. Increase in the incidence of ASD in this center cannot explain by any solid evidence from the present study.
PMID: 16241015 [PubMed - indexed for MEDLINE]
In 1992, Thailand began a universal hepatitis B vaccination program under WHO's EPI, or Extended Program of Immunization. I doubt they were injecting neonates with thimerosal-free hep B shots.
Volume: 27S3 • September 2001
Viral Hepatitis and Emerging Bloodborne Pathogens in Canada
http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/01vol27/27s3/27s3k_e.html
Hepatitis B and its Control in Southeast Asia and China Zhiyong Hong, Shimian Zou, Antonio Giulivi
Hepatitis B is one of the major infectious diseases of mankind: of 360 million chronic carriers worldwide, 78% are in Asia, 16% in Africa, 3% in South America, and 3% in Europe, North America, and Oceania combined. HBV infection is the most common cause of chronic hepatitis, liver cirrhosis and HCC worldwide(1).
In order to combat HBV infection and subsequent carriage, most East Asian and Southeast Asian countries introduced mass vaccination programs during the late 1980s and mid-1990s, which have resulted in a drastic decline in the HBV carrier rate and the number of patients with HCC.
Although HBV prevalence is low in Canada, changes in the epidemiology of this disease in other parts of the world may have a significant impact on the health of Canadians. Therefore, it is important to closely and continuously monitor the status of the disease in the world, especially in areas where HBV is endemic.
Indonesia The island of Lombok, east of Bali in Nusa Tenggara Barat Province, was the first to introduce a mass infant hepatitis B immunization project in Indonesia, which ran from November 1987 to October 1991(2). The Lombok Project clearly demonstrated the feasibility of incorporating HBV vaccine into the Expanded Program on Immunization (EPI) in a way that can significantly reduce chronic HBV infection and strengthen the EPI. The success of the Lombok Project was the basis for a national program of universal infant immunization in Indonesia. Four provinces were added to the program in 1991-1992, and the program was further expanded to 10 provinces in 1992-1993, requiring 4.5 million annual vaccine doses. The overall reduction in the prevalence of HBsAg among fully vaccinated children (less than 4 years old) fell from 6.2% to 1.9%, for a reduction of 70%.
Malaysia From February 1997 to July 1999, a total of 79,103 individuals, including university students, health care workers, and primary and secondary school students, participated in a prospective study of hepatitis B. In all, 92.9% were Chinese, 4.8% were Malays, 2.1% were Indians, and 0.1% were from other ethnic groups(3). The age of the participants ranged from 5 to 60 years old. Demographic data and history of hepatitis B vaccination were obtained from each participant, and testing was carried out for HBsAg and anti-HBs. The overall prevalence of HBsAg was 1.5%. The rate among the Malays, Chinese, and Indians was 1.5%, 1.5%, and 0.3% respectively. Among all participants, 62.4% had been vaccinated with all three doses of HBV. Chinese participants were found to have the highest vaccination rate (64.5%), followed by Indians (37.8%), and Malays (32.7%). The rate of endemic HBV in Malaysia is now low, as its vaccination programs and possibly other intervention measures have successfully reduced the incidence of the infection(4).
The Philippines The prevalence of chronic HBV infection in the Philippines, as indicated by HBsAg positivity, has been found to range from 2.0% to 16.5%, with an average of 12.0%, in a study of rural villagers(5). In a study assessing the feasibility and effectiveness of incorporating hepatitis B vaccine into the national EPI, HBsAg positivity decreased to 2% during the last 10-year period (1987-1996) in the Philippines(6).
The Republic of Singapore In Singapore, the HBsAg carrier rate for the general population was 9% to 10% in 1980-1981. A national childhood hepatitis B vaccination program was formulated and implemented in phases, starting with babies born to carrier mothers on October 1, 1985, and finally extending to all newborns on September 1, 1987. During the period from 1994 to 1996, more than 90% of children completed the full schedule of immunization by 1 year of age, and 85% had evidence of vaccination at school entry at age 6. Follow-up of two cohorts of vaccinated children showed that perinatal transmission was reduced by 80% to 100%. Horizontal transmission also declined through other public health measures. The incidence of acute hepatitis B declined from 10.4 per 100,000 in 1985 to 4.8 per 100,000 in 1996(7). The vaccination coverage in newborns reached 100%, and the HBsAg positive rate declined to 2% to 3% in 1997 and 1998 in randomized population groups and in new blood donors. The acute HBV morbidity had fallen continuously from 10.4 per 100,000 in 1985 to 4.5 per 100,000 in 1997, and the incidence of HCC continued to decline(8).
Thailand In 1992, hepatitis B vaccine was included in the EPI on a nationwide scale in Thailand. Recent data on the immunization program against hepatitis B demonstrate a steady decline in the incidence of HBV carriers among the Thai population during the period from 1981 to 1991. For example, the prevalence of HBV carriers among blood donors and students decreased from 8.2% and 6.6 % in 1987 to 6.5% and 5.2% in 1991 respectively(9). Current data from an epidemiologic survey in Songkhle Province in the south of Thailand demonstrated an overall prevalence of HBV carriers of 0.55% among children less than 15 years of age(10). It has been clearly shown that hepatitis B immunization as part of the EPI is highly efficient in protecting newborns from infection.
Viet Nam Blood donors from two cities in Viet Nam were tested for markers of HCV and HBV infection. Among 491 donors in Ho Chi Minh City and 499 donors in Hanoi City, HBsAg carrier rates were 3.1% and 3.0% respectively(11). There is no report about the HBsAg carrier rate in the general population.
China (mainland) HBV infection rates reported for university students ranged from 4.5% to 19.4% during the period from the mid-1980s to the early 1990s(12). The HBsAg carrier rate in China showed a substantial decrease after the implementation of the WHO strategy. Zeng et al carried out a randomized two-stage household sampling survey at 112 disease surveillance points from 25 provinces, autonomous regions, and municipalities of China in 1996(13). The results showed that the hepatitis B vaccination coverage rates among neonates were 96.7% in 1993 and 97.5% in 1994-1996 in urban areas, and 50.8% in 1993 and 73.9% in 1994-1996 in rural areas. Vaccination coverage rates among 7-9 year-old students in 1994 in urban and rural areas were 97.5% and 73.9% respectively. Lu et al conducted a sampled survey on hepatitis A, B, and C in Yunnan province, China, in 1998(14). The prevalence of HBsAg was 2.0% in 452 serum samples collected from pupils aged 6-12 years old in three different counties. Zhang et al(15) determined the persistence of immunity in neonates born to HbsAg positive mothers following HB immunization with different schedules(15). In total, 203 neonates were followed-up continuously for 6 years for anti-HBs and HBsAg. Anti-HBs in the neonates was maintained in greater than 90% of the children during those years. None of the children tested positive for HBsAg. A booster dose of vaccine after the primary immunization seemed unnecessary for children 6-10 years old. Zhu et al(16) reported the results of the status of hepatitis B vaccination in China from the 1999 National Coverage Study. A total of 25,878 children aged 18-34 months from 31 provinces were surveyed. The national hepatitis B vaccine coverage (receipt of three doses) was 70.7%.
Hong Kong A campaign to promote screening and vaccination for hepatitis B in students at the University of Hong Kong was described by Marshall (1995)(17). Of eligible students, 98% had the first dose of vaccine, and greater than 96% completed the full course of three doses. After vaccination, the prevalence of HBsAg was 3.6%; male students showed a significantly higher prevalence (4.5%) than female students (2.9%). These levels are about one-third of the prevalence levels found in the same age group in the general population in Hong Kong. The author recommended that students at secondary schools and post-secondary educational institutions in Hong Kong should be offered serologic screening and vaccination for hepatitis B.
Taiwan In the early 1980s, 15% to 20% of the population of Taiwan were estimated to be HBV carriers. A program of mass vaccination against hepatitis B was launched in 1984. In the first 2 years of the program, newborns of all HbsAg positive mothers were vaccinated. Since 1986, all newborns, and then pre-school children, primary school children, adolescents, young adults, and others have also been vaccinated. Vaccination coverage was greater than 90% for newborns, 79% of pregnant women being screened for HBsAg. The proportion of babies who were born to highly infectious carrier mothers and became carriers decreased from 86% to 96% to 12% to 14%, whereas the decrease was from 10% to 12% to 3% to 4% for babies of less infectious mothers. Between 1989 and 1993, the prevalence of HBsAg among children aged 6 years also fell, from 10.5% to 1.7%. The average annual incidence of HCC among children aged 6-14 years decreased significantly, from 0.7/100,000 in 1981-1986 to 0.4/100,000 in 1990-1994. Similarly, the annual incidence of HCC among children aged 6-9 years declined from 0.5/100,000 for those born in 1974-1984 to 0.1/100,000 for those born in 1986-1988. These data demonstrate that the mass vaccination program has been effective in controlling chronic HBV infection and in preventing liver cancer in Taiwan. If a 90% coverage rate of hepatitis B vaccination in newborns can be maintained, the carrier rate of HBsAg in Taiwan is expected to decline to lower than 0.1% by year 2010(18).
Summary The most recent data from Southeast Asia and China show that there have been substantial decreases in the incidence and prevalence of hepatitis B following the immunization strategies that have been implemented in that region. However, it should also be noted that the overall HBV prevalence rate is nevertheless high in the area, especially among children and adults born before the introduction of the current hepatitis B vaccination programs. Both aspects of the epidemic pattern in that area may have implications for decision making regarding the prevention and control of hepatitis B in Canada.
References
- Kane MA. World-wide epidemiology of hepatitis B. Soz Praventivemed 1998;43:S24-6.
- Ruff TA, Gertig DM, Otto BF et al. Lombok hepatitis B model immunization project: toward universal infant hepatitis B immunization in Indonesia. J Infect Dis 1995;171(2):290-96.
- Ng KP, Saw TL, Baki A et al. APASL Commemorative International Congress on Viral hepatitis prevention and Control. Singapore, 16-19
February 2000:80. - Andre F. Hepatitis epidemiology in Asia, the Middle East and Africa.
Vaccine 2000;18:S20-2. - Lansang MA. Epidemiology and control of hepatitis B infection: a perspective from the Philippines. Asia Gut 1996;38(S2):43-7.
- Subida RD, Zhang ZW, Agetano MC et al. Hepatitis B and C virus infection prevalence among women in Manila, the Philippines. Southeast Asian J Trop Med Public Health 1997;28(4):683-88.
- Goh KT. Prevention and control of hepatitis B virus infection in Singapore. Ann Acad Med Singapore 1997;26(5):671-81.
- Oon CJ, Goh KT, Tan KL et al. APASL Commemorative International Congress on Viral hepatitis prevention and Control. Singapore, 16-19
February 2000:62. - Tanprasert S, Somjitta S. Trend study on HBsAg prevalence in Thai
voluntary blood donors. Southeast Asian J Trop Med Public health 1993;24(Suppl 1):43-5. - Chub-uppakarn S, Panichart P, Theamboonlers A et al. Impact of the hepatitis B mass vaccination program in the southern part of Thailand. Southeast Asia. J Trop Med Public Health 1998;29(3):464-68.
- Song P, Duc DD, Hien B et al. Markers of hepatitis C and B virus infections among blood donors in Ho Chi Minh City and Hanoi. Vietnam Clin Diagn Lab Immunol 1994;1(4):413-18.
- Zhang S, Chen Y. HBV serum marker detection and relative factor analysis of 2925 new students. Public Health 1998;112(4):257-59.
- Zeng X, Yang G, Liao S. A study on the coverage, strategy and cost of
hepatitis B vaccination in China, 1996. J Chinese Epidemiology 1998;19(5):277-81. - Lu L, Ma Y, Xie Z et al. A sampling survey on the epidemic status of
hepatitis A, B, C among the pupils in the Yunnan province's countryside. China Public Health 1998;14(11):647. - Zhang XC, Ying Y, Shen L et al. Follow-up on hepatitis B immunized neonates born to HBsAg positive. J Chinese Preventive Medicine 1998;32(2):97-99.
- Zhu X, Zhang X, Wang L et al. Status of hepatitis B vaccination in China: results from the 1999 national coverage study. Antiviral Therapy 2000;5:S37.
- Marshall IB. Screening and vaccination for hepatitis B in Hong Kong
university students. J Am Public Health 1995;44(2):59-62. - Huang K, Lin S. Nationwide vaccination: a success story in Taiwan.
Vaccine 2000;18(S1):S35-8.
