Vaccines to Prevent Hepatitis A and Hepatitis B*
Hepatitis A and Hepatitis B are Serious Public Health Problems Outbreaks of hepatitis A occur more easily in overcrowded areas where poor sanitary conditions exist. Hepatitis A virus (HAV) is primarily transmitted through the fecal-oral route, when a person puts something in his or her mouth (such as food or a beverage) that has been contaminated with the feces of a person infected with HAV. Outbreaks also occur among injection drug users (IDUs); transmission may result from sharing needles and drug preparation equipment, sexual contact, or poor hygiene. HAV infection can be very severe in those who already have chronic liver disease from hepatitis B virus (HBV) or hepatitis C virus (HCV) infection. During epidemic years, as many as 35,000 cases of hepatitis A have been reported. Once infected with HAV, people develop a protective immunity. They cannot get hepatitis A again, and they are no longer infectious to others.
In 2000, an estimated 73,000 people in the U.S. were newly infected with hepatitis B virus. About 5,000 die every year from liver disease caused by HBV infection. IDUs and people with high-risk sexual behaviors (such as unprotected sex with multiple partners) are at high risk of HBV infection. About 2%-6% of those who were initially infected as older children or adults never clear the virus from their bodies. They develop chronic HBV infection and can transmit HBV to others. Much higher percentages of those infected as babies (90%) and young children (30%) become chronically infected. About 1.25 million people in the U.S. have chronic HBV infection. In about 15%-25% of these individuals, the virus causes gradual, progressive liver disease, leading to cirrhosis, liver cancer, or liver failure.
Vaccines are Available to Prevent Hepatitis A and Hepatitis B
Hepatitis A vaccine
Two hepatitis A vaccines are licensed in the U.S. for use in people aged 2 years and older. Each is given in 2 doses, 6 to 18 months apart. Immunization against hepatitis A is recommended for people at risk of getting infected or who may become seriously ill if infected (see chart). It is estimated that the protection against HAV infection provided by the vaccine will last for at least 20 years.
Who Should be Immunized Against Hepatitis A?
Hepatitis B vaccine
Immunization against HBV infection is recommended for all babies, children and adolescents aged 0-18 years, and people in high-risk groups (see chart). Two hepatitis B vaccines are approved for use in the U.S. Each is usually given in three doses over a 6-month period. A 2-dose regimen (the second dose is given 4-6 months after the first) for one of the vaccines has been approved for use in persons 11-15 years old.
In 2001, a combined hepatitis A and hepatitis B vaccine became available. This vaccine is approved for use in people aged 18 and older and is given in 3 doses over a 6-month period.
Developing a Vaccine for Hepatitis C is More Difficult
In all viral infections, the virus reproduces after it enters the body. When HCV reproduces, it produces a large number of viruses that differ slightly from each other in their genetic makeup. Scientists believe that this genetic diversity allows HCV to evade the body's immune system and it may be the reason why such a high percentage of people infected with HCV (75%-85%) develop chronic infection. This genetic diversity is also the reason why an effective hepatitis C vaccine has not yet been developed. In contrast, HAV and HBV are more stable viruses and do not change very much genetically when they reproduce. This allows the body's immune system to effectively clear the virus and to develop a lifelong immunity to the disease and is the reason why scientists have been able to produce effective vaccines.
Who Should be Immunized Against Hepatitis B?
Immunizing IDUs against Hepatitis A and Hepatitis B is Especially Important
Approximately 50%-70% of IDUs become infected with HBV within 5 years of beginning to inject drugs. This means that IDUs should be immunized against HBV as soon after starting to inject as possible. Outbreaks of hepatitis A also occur among IDUs. If they are not already immune because of previous infection, IDUs should be immunized against this hepatitis virus as well.
However, many IDUs lack a regular source of health care. When they do receive care, it is often in settings, such as emergency rooms, that do not routinely offer hepatitis A and hepatitis B immunization. The myths and stigma surrounding IDUs - beliefs that they can't be reached by outreach initiatives, that they can't or won't get the full vaccine series, and that they won't take other protective measures - also make it difficult to stimulate efforts to immunize IDUs.
Currently, most resources are dedicated to ensuring hepatitis B immunization of babies, children, and adolescents through infant immunization schedules and school admission immunization requirements. Health care providers don't necessarily think about the need to immunize adults or routinely ask about high-risk behaviors that might suggest a need for immunization. In addition, funds for large-scale immunization programs for adults are limited.
Community-based organizations who are working on HIV, IDU, and substance abuse issues are becoming increasingly aware of the importance of viral hepatitis and the need to immunize high-risk groups. However, limited staffing, expertise, and funding for vaccines may make it difficult for them to add this issue to their existing efforts.
New Initiatives are Turning Challenges into Opportunities
New federal hepatitis A and hepatitis B vaccination initiative.The Centers for Disease Control and Prevention's National Center for Infectious Diseases (NCID), National Center for HIV, STD, and TB Prevention (NCHSTP), and National Immunization Program (NIP) and the Substance Abuse and Mental Health Services Administration's Center for Substance Abuse Treatment (CSAT) have launched a new initiative. This effort is aimed at raising awareness of the importance of hepatitis A and hepatitis B immunization among highrisk individuals seen in public health outreach and service settings, such as STD clinics, HIV counseling and testing sites, correctional facilities, and substance abuse treatment facilities. The initiative will promote the availability and use of vaccines. It will also encourage staff of these settings to work with state immunization staff to develop estimates of needs for vaccines, review readiness of state-level programs to receive and administer immunizations, and develop strategies to promote immunization among high-risk individuals.
Washington State hepatitis B immunization program. An outbreak of hepatitis B among IDUs in Pierce County, Washington, detected in 2000, led to an innovative and successful immunization collaboration among the health and corrections departments and community-based organizations, particularly the local syringe exchange program (SEP). The county health department opened the first immunization clinics at the SEP and the health department. Additional immunization clinics were later opened at the county jail, a soup kitchen, and a substance abuse treatment program for women. Slightly more than 60% of those who began the vaccine series reported that they had ever injected drugs.
Participants did not have to pay for the immunization and also received a $5 reimbursement for travel with each dose. Just over half (53%) of the 1,981 participants who received the first dose returned for the second dose, and 27% completed the series of three doses. Completion rates for IDUs and non-IDUs were very similar. To Learn More About This Topic Read the overview fact sheet in this series - "Viral Hepatitis and Injection Drug Use." It provides basic information, links to the other fact sheets in this series, and links to other useful information (both print and Internet). Visit websites of the CDC and the Academy for Educational Development for these and related materials:Preventing Blood-borne Infections Among Injection Drug Users: A Comprehensive Approach, which provides extensive background information on HIV and viral hepatitis infection in IDUs and the legal, social, and policy environment, and describes strategies and principles of a comprehensive approach to addressing these issues.
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*Based on information published by the Centers for Disease Control.
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