The hepatitis A vaccine can prevent people from getting the disease by priming their immune system to develop these protective antibodies.
What Is the Hepatitis A Vaccine?
The hepatitis A vaccine consists of an inactivated version of hepatitis A virus, or HAV. There are two hepatitis A vaccines available: HAVRIX and VAQTA, which are produced by GlaxoSmithKline and Merck, respectively. The first dose of the vaccine causes more than 95 percent of adults and more than 97 percent of children to develop protective antibodies, according to the CDC. Nearly 100 percent of people will develop the antibodies after a second dose of the vaccine (given about six months after the first dose). Research suggests the two vaccines are similarly effective at protecting against clinical hepatitis A. HAVRIX, which first became available in 1995, was 94 percent effective in preventing hepatitis A in a study of 40,000 Thai children between one and 16 years of age who were living in villages with high HAV disease rates, according to the CDC. Comparatively, VAQTA, which first became available in 1996, was 100 percent effective in preventing hepatitis A in a study of 1,000 New York City children between two and 16 years of age who were living in a community with a high HAV disease rate. China and some areas of India use another type of hepatitis A vaccine that contains live, attenuated (weakened) strains of HAV. This vaccine has also been shown to be safe and highly protective against hepatitis A, according to the World Health Organization (WHO).
Who Should Be Vaccinated?
Today, the CDC recommends that all children receive their first dose of the hepatitis A vaccine when they’re between one and two years old, and a second dose of the vaccine six to 12 months later. However, children who don’t receive the first dose before reaching two years of age can still receive the vaccine at a later time. Adults who didn’t receive the vaccine as children should also get the vaccine if they’re at a high risk of contracting HAV. This includes people who:
Live in a community with high hepatitis A ratesUse illegal drugs (including non-injected drugs)Have long-term liver disease or a disorder that affects blood clotting, such as hemophiliaAre men who have sex with other menHave an occupational risk of hepatitis A, such as from working with HAV in a research lab or with primates infected with HAV
People who travel to countries with high hepatitis A rates are also at an increased risk of getting the disease, and may need to get the vaccine. The CDC recommends that older adults, people with weakened immune systems, and those with chronic liver disease or another chronic medical condition receive an initial dose of the vaccine and a dose of immune globin (IG) antibodies within two weeks of travelling to areas with high hepatitis A rates. People who choose not to receive the vaccine, or cannot receive it because they’re under 12 months of age or allergic to the vaccine’s components, should receive a single dose of IG before travelling. This can prevent a hepatitis A infection for up to three months. TWINRIX, a combination vaccine that contains vaccines for both hepatitis A and hepatitis B, has also been available since 2001. TWINRIX is typically administered in three doses over a period of six months.
Hepatitis A Vaccine Side Effects
The hepatitis A vaccine may cause several symptoms that last for one to two days including:
Muscle soreness at the site of injectionHeadacheLoss of appetiteTiredness
In rare cases, people experience serious allergic reactions to the vaccine within a few hours of injection.
