Hepatitis A vaccine
||The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. (June 2011)|
|Target disease||Hepatitis A|
|Pregnancy cat.||Safety undetermined, risk likely low|
|Legal status||Rx-only (US)|
| (what is this?)
Hepatitis A vaccine is a vaccine against the hepatitis A virus. The first successful vaccine against it was invented by Maurice Hilleman at Merck.1 The vaccine protects against the virus in more than 95% of cases and provides protection from the virus for at least fifteen years.2 There are two types of vaccines: one type contains inactivated hepatitis A virus, the other contains a live but attenuated virus. Both types stimulate active immunity against a future infection.
Within the US, the vaccine was first phased in around 1996 for children living in high-risk areas. In 1999, it was spread to areas with elevating levels of infection. In the US today, the vaccine is strongly recommended for all children 12 to 23 months of age in an attempt to eradicate the virus nationwide. Although the original FDA license for Havrix by GlaxoSmithKline is dated in 1995,3 it has been in use in Europe since 1993.
According to the US Centers for Disease Control and Prevention, the following people should be vaccinated: all children over one year of age, people whose sexual activity puts them at risk, people with chronic liver disease, people who are being treated with clotting factor concentrates, people working within close proximity to the virus, and people who are living in communities where an outbreak is present.4 Hepatitis A is the most common vaccine-preventable virus acquired during travel,5 so people travelling to places where the virus is common like the Indian subcontinent, Africa, Central America, South America, the far East, and Eastern Europe should be vaccinated.46
The vaccine should be given in the muscle of the upper arm and be given in two doses for the best protection. The initial dose of the vaccine should be followed up by a booster six to twelve months later.4 Protection against hepatitis A begins approximately two to four weeks after the initial vaccination.46 Protection is proven to last at least 15 years and is estimated to last at least 25 years if the full course is administered.2
A Cochrane review found that both types of vaccines offer significant protection, for at least two years with the inactivated vaccine and at least five years with the attenuated vaccine. The review also found evidence to conclude that the inactivated vaccine was safe, but required more high quality evidence to assess the safety of the attenuated vaccine.7
This may not be a comprehensive list of all commercial hepatitis A vaccines available. Please note that the definition of "U" (units) may vary between manufacturers depending on what test they use to measure hepatitis A antigen in their products.
- Avaxim: made by Sanofi Pasteur. Inactivated hepatitis A virus produced in MRC-5 cells. Each dose contains 160 U of antigen adsorbed on aluminium hydroxide (0.3 mg Al).8
- Epaxal: made by Crucell. Also sold under the brand names HAVpur and VIROHEP-A. This vaccine consists of virosomes, artificial particles composed of synthetic lipids and influenza proteins in addition to the hepatitis A antigen. It does not contain aluminium.9
- Havrix: made by GlaxoSmithKline. Inactivated hepatitis A virus produced in MRC-5 cells. Each adult dose contains 1440 ELISA units of viral antigen adsorbed on aluminium hydroxide (0.5 mg Al). The pediatric (child) doses contain half the amount of viral antigen and aluminium.10
- Healive: made by Sinovac. Inactivated hepatitis A virus cultured in human diploid cell, followed by harvest, purification, inactivation, and aluminium adsorption. Each adult dose contains 500 U of viral antigen. The pediatric dose contains 250 U of viral antigen.
- Vaqta: made by Merck. Inactivated hepatitis A virus produced in MRC-5 cells. An adult dose contains 50 U of antigen adsorbed onto 0.45 mg of aluminium (as aluminium hydroxyphosphate sulfate); a child dose contains half the amounts of antigen and aluminium.citation needed
- Offit PA (2007). Vaccinated: One Man's Quest to Defeat the World's Deadliest Diseases. Washington, DC: Smithsonian. p. 107. ISBN 0-06-122796-X.
- Ott JJ, Irving G, Wiersma ST (December 2012). "Long-term protective effects of hepatitis A vaccines. A systematic review". Vaccine 31 (1): 3–11. doi:10.1016/j.vaccine.2012.04.104. PMID 22609026.
- "Hepatitis A Vaccine Information". Vaccine Information. ImmunizationInfo. Retrieved 2008-06-19.
- "Hepatitis A Vaccine: What you need to know". Vaccine Information Statement. CDC. 2006-03-21. Retrieved 2007-03-12.
- "Hepatitis, Viral, Type A". Travelers' Health: Yellow Book (CDC). Retrieved 2007-03-12.
- "Hepatitis A: Introduction". NHS Direct. 2006-10-10. Archived from the original on 2007-03-10. Retrieved 2007-03-12.
- Irving GJ, Holden J, Yang R, Pope D (2012). "Hepatitis A immunisation in persons not previously exposed to hepatitis A". Cochrane Database Syst Rev 7: CD009051. doi:10.1002/14651858.CD009051.pub2. PMID 22786522.
- Patient Information Leaflet, sanofi pasteur, July 2010. Archived on the electronic Medicines Compendium of the UK. Accessed 30 November 2010.
- Epaxal, Crucell website. Accessed 30 November 2010.
- Full Prescribing Information, GlaxoSmithKline, July 2010. Archived on FDA website. Accessed 30 November 2010.