Thursday, November 1, 2012

Hepatitis B


Andrew received his first hepatitis B vaccine minutes after he was born. There are several reasons for starting the hepatitis B vaccine series at birth. To understand them, we first need to understand the epidemiology and natural history of hepatitis B virus (HBV) infection.

Andrew shortly after receiving his first dose of hepatitis B vaccine

Hepatitis B virus transmission

Like human immunodeficiency virus (HIV), HBV is transmitted through blood and body fluids. Unlike HIV, HBV can survive outside of the human body and remain infectious over a week. HBV is also 50 to 100 times more infectious than HIV.

Worldwide, most HBV infections are acquired perinatally; that is, the virus was passed from an infected mother during childbirth. Infants who become infected with HBV are much less likely to develop symptoms of acute hepatitis B and much more likely to develop chronic HBV infection than adults who acquire the infection.

Age at infection:

Acute hepatitis B
Risk
Under 5 years of age
<10%
Over 5 years of age
30% to 50%
Chronic HBV infection
 
Infants
90%
1 to 4 years of age
30%
Adults
<5%

Transmission of HBV also occurs among household contacts of people with HBV infection, through sexual contact, through injection drug use, and is an occupational risk for people with frequent contact with blood and/or body fluids (e.g., health care providers. I was required to take the hepatitis B vaccine series when I started nursing school). Although hepatitis B was called "serum hepatitis" because it was frequently transmitted through blood transfusions, blood is now screened for hepatitis and other pathogens, so there is an extremely low risk of HBV infection from receiving a blood transfusion.

Hepatitis B infection

In my previous post on hepatitis, I briefly described the symptoms of acute hepatitis: jaundice, fatigue, malaise, muscle and joint pain, nausea and vomiting, and pain over the liver. Although fulminant liver failure can occur as a result of infection with any of the hepatotropic viruses (hepatitis A, B, C, D, and E viruses), most people recover from acute hepatitis without serious consequences.

People with chronic HBV infection can be completely asymptomatic for decades. Chronic HBV infection increases the risk for liver cirrhosis and hepatocellular carcinoma (HCC, liver cancer). Babies can be infected at birth, show no signs of being infected, and then develop fatal liver disease later in childhood or as adults.

Hepatocellular carcinoma
CDC/Patricia Walker, M.D., Regions Hospital, MN
 
Cancer vaccine

Studies of hepatitis B vaccine have been ongoing since the 1980s. Vaccinating children against hepatitis B has reduced the incidence of HCC in children who received the vaccine in Taiwan, and Thailand and eliminated hepatitis B-associated HCC in Alaska Native children. For this reason, hepatitis B vaccine is considered the first cancer vaccine.

Vaccine safety

Hepatitis B vaccines contain a single viral surface antigen that is produced by yeast using recombinant DNA, similar to the way insulin (Humulin®, Novolin®) is made using yeast or the bacteria E. coli. Hepatitis B vaccines do not contain HBV and HBV is not used in the production of hepatitis B vaccines.

The safety of hepatitis B vaccines has been studied since the introduction of plasma-derived vaccines in the 1980s. The Institute of Medicine (IOM) has published two reviews of hepatitis B vaccine safety. The only adverse effect identified as causally associated with hepatitis B vaccines is a severe allergic reaction (anaphylaxis) in people who are allergic to yeast. This association was based on 10 cases of anaphylaxis in people who had received a hepatitis B vaccine. Another review of adverse reaction data found that hepatitis B vaccine-associated anaphylaxis in children is rare.

Why vaccinate babies against hepatitis B?

The most common way HBV is transmitted is from mother to child during childbirth. Babies who become infected with HBV are more likely to develop chronic HBV infection and less likely to have symptoms of acute hepatitis then older children and adults. Therefore, infancy is the most dangerous time to be infected with HBV. Immunizing babies against hepatitis B can prevent HBV infection and has been found to reduce the incidence of HCC in children.

The reason for universal immunization against hepatitis B can be found in the title of the Advisory Committee on Immunization Practices (ACIP) recommendations: A comprehensiveimmunization strategy to eliminate transmission of hepatitis B virus infection in the United States. I discussed disease eradication in and disease elimination previous posts. Disease elimination is "the reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts" (Dowdle, 1999); that is, transmission of the disease no longer occurs in a specific area of the world (in contrast to eradication, in which disease transmission no longer occurs anywhere in the world).

The study in Alaska demonstrated that HBV infection and HCC can be eliminated from a defined geographic region using universal childhood hepatitis B immunization. The incidence of HBV infection in children throughout the U.S. has decreased dramatically since the introduction of hepatitis B vaccines.
CDC, 2004


Mary 

Yesterday, the eve of All Saints Day, my mother-in-law Mary Esvelt died from a complication of the malignant brain tumor with which she was diagnosed on Mother's Day of this year.

I know of no person more dedicated to serving the Lord than Mary. She delighted in her ministries and teaching Christian belief and values.

I met the Esvelts while taking care of Seth, Holly's brother, who suffered a severe traumatic brain injury in a motor vehicle accident. Seth has remained in a minimally conscious state since the injury. Mary and Craig have cared for Seth at home 24/7 since Holly and I were married seven years ago.

Despite the physical pain she suffered from rheumatoid arthritis and the emotional pain of having a severely disabled son, Mary remained firm in her faith and tireless in her service to others. Mary was a blessing to all who knew her.

Of course, I admire Mary most for being the mother of my precious wife Holly.

"We do not want you to be unaware, brothers, about those who have fallen asleep, so that you may not grieve like the rest, who have no hope."
- 1 Thessalonians 4:13

References

Bohlke, K., Davis, R. L., Marcy, S. M., Braun, M. M., DeStefano, F., Black, S. B. et al. (2003). Risk of anaphylaxis after vaccination of children and adolescents. Pediatrics, 112(4), 815-820. http://www.ncbi.nlm.nih.gov/pubmed/14523172.

Centers for Disease Control and Prevention. (2004). Incidence of acute hepatitis B – United States, 1990-2002. Morbidity and Mortality Weekly Report, 52(51 & 52), 1252-1254. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5251a3.htm.

Centers for Disease Control and Prevention. (2005). A comprehensive immunization strategy to eliminate transmission of hepatitis B virus infection in the United States. Recommendations of the Advisory Committee on Immunization Practices (ACIP). Part 1: Immunization of infants, children, and adolescents. Morbidity and Mortality Weekly Report, 54(16), 1-23. http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5416a1.htm.

Chang, M. H., You, S. L., Chen, C. J., Liu, C. J., Lee, C. M., Lin, S. M., et al. (2009). Decreased incidence of hepatocellular carcinoma in hepatitis B vaccinees: a 20-year follow-up study. Journal of the National Cancer Institute, 101(19), 1348-1355. http://jnci.oxfordjournals.org/content/101/19/1348.long.

Dowdle, W. R. (1999). The principles of disease elimination and eradication. Morbidity and Mortality Weekly Report, 48(Supple. 1), 23-27. http://www.cdc.gov/mmwr/preview/mmwrhtml/su48a7.htm.

Institute of Medicine. (2002). Hepatitis B vaccine and demyelinating neurological disorders. Washington D. C.: National Academies Press. http://books.nap.edu/catalog.php?record_id=10393.

Institute of Medicine. (2012). Adverse effects of vaccines: evidence and causality. Washington D.C.: National Academies Press. http://www.nap.edu/catalog.php?record_id=13164.

Kew, M. C. (2010). Epidemiology of chronic hepatitis B virus infection, hepatocellular carcinoma, and hepatitis B virus-induced hepatocellular carcinoma. Pathologie Biologie, 58(4), 273-277. http://www.ncbi.nlm.nih.gov/pubmed/20378277.

Mast, E. E. & Ward, J. W. (2008). Hepatitis B vaccine. In S. A. Plotkin, W. A. Orenstein, & P. A. Offit (Eds.) Vaccines (5th Ed.) [Electronic version].

McMahon, B. J., Bulkow, L. R., Singleton, R. J., Williams, J., Snowball, M., Homan, C. et al. (2011). Elimination of hepatocellular carcinoma and acute hepatitis B in children 25 years after a hepatitis B newborn and catch-up immunization program. Hepatology, 54(3), 801-807. http://www.ncbi.nlm.nih.gov/pubmed/21618565.

Ni, Y. H. & Chen, D. S. (2010). Hepatitis B vaccination in children: the Taiwan experience. Pathologie Biologie, 58(4), 296-300. http://www.ncbi.nlm.nih.gov/pubmed/20116181.

Park, N. H., Chung, Y. H., & Lee, H. S. (2010). Impacts of vaccination on hepatitis B viral infections in Korea over a 25-year period. Intervirology, 52(1), 20-28. http://www.ncbi.nlm.nih.gov/pubmed/20068337.

Tajiri H, Tanaka H, Brooks S & Takano T. (2011). Reduction of hepatocellular carcinoma in childhood after introduction of selective vaccination against hepatitis B virus for infants born to HBV carrier mothers. Cancer Causes & Control, 22(3), 523-7. http://www.ncbi.nlm.nih.gov/pubmed/21191808.

Viviani, S., Carrieri, P., Bah, E., Hall, A. J., Kirk, G. D., Mendy, M. et al. (2008) Gambia Hepatitis Intervention Study.20 years into the Gambia Hepatitis Intervention Study: assessment of initial hypotheses and prospects for evaluation of protective effectiveness against liver cancer. Cancer Epidemi0ology, Biomarkers & Prevention, 17(11), 3216-3223. http://cebp.aacrjournals.org/content/17/11/3216.long.

Wasley, A., Kruszon-Moran, D., Kuhnert, W., Simard, E. P., Finelli, L., & Bell, B. (2010). The prevalence of hepatitis B virus infection in the United States in the era of vaccination. Journal of Infectious Diseases, 202(2),192-201. http://jid.oxfordjournals.org/content/202/2/192.long.

Wichajarn, K., Kosalaraksa, P., & Wiangnon, S. (2008). Incidence of hepatocellular carcinoma in children in Khon Kaen before and after national hepatitis B vaccine program. Asian Pacific Journal of Cancer Prevention, 9(3), 507-509 http://www.apocp.org/cancer_download/Volume9_No3/507%20Wichajarn%20.pdf.

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