New Study Shows Hepatitis A Vaccine Effective For 10 years

A recent, first-of-its kind study on vaccine effectiveness found that children younger than 2 who receive the hepatitis A vaccine are protected for 10-years.

Umid Sharapov, a CDC epidemiologist, who led the new study, said this was the first study to examine the effectiveness of a two-dose inactivated hepatitis A vaccine in children younger than two years over a 10-year period.

What Is Hepatitis A?

Hepatitis A is an inflammatory disease of the liver. People become infected with hepatitis A when they orally ingest the fecal matter—even just microscopic traces—of infected individuals. That is why the virus is typically found in areas with poor sanitation where it is transmitted through contaminated food and water.

The World Health Organization estimates that 1.4 million cases of hepatitis A infection occur worldwide every year.

New Study On Hepatitis A Vaccine Effectiveness

The researchers examined nearly 200 infants and toddlers who were born at full term and healthy at 6 months of age. The children were divided into three groups based on their age: The first group was comprised of babies between 6 months and 12 months old, toddlers between 12 months and 18 months old formed the second group and those from 15 months to 21 months of age made up the third group.

The children’s mothers also were tested for hepatitis A antibodies.

The children’s hepatitis A antibody levels were measured at 1 month and 6 months. The researchers also conducted follow-up assessments at 3, 5, 7 and 10 years old, after the children received their second dose of the hepatitis A vaccine.

The study found that one month after they received the second dose of the vaccine, children in all three groups showed signs of protection from the virus. At the 10-year follow-up, most of the children were still protected from the virus.

The researchers noted that 7 percent of the 6- to 12-month-old babies born to mothers who did not have hepatitis A antibodies did not retain the protection from the virus provided by the vaccine. Moreover, 11 percent of the children from this group whose mothers did have hepatitis A antibodies also lost their protection.

The researchers also found that 4 percent of the children between 15 months and 21 months old who were born to women without hepatitis A antibodies no longer had protection from the virus after 10 years.

“Our study demonstrates that [the effects of] a hepatitis A [vaccine] persists for at least 10 years after primary vaccination … when administered to children at ages 12 months and older, regardless of their mothers’ anti-hepatitis A status,” Dr. Sharapov said.  “These findings support current CDC … guidelines for routine administration of two doses of inactivated hepatitis A vaccine to all children in the U.S., beginning at the age of 12 months.”

The study authors added that a future booster dose may be necessary for children to maintain protection against hepatitis A.

The study was published in the August issue of the journal Hepatology.

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