What is hepatitis A?
Hepatitis A virus (HAV) is present worldwide and is the agent of one of the most widespread infections transmitted via the fecal-oral route. In countries with poor hygiene and consequent wide presence of feces in the environment, the vast majority of subjects is infected within 5 years of age (usually without any sign or symptom of acute hepatitis), thus acquiring life-long immunity. Outbreaks and epidemics are rare due to the high herd immunity level in the population.HAV infection is transmitted both by direct contact with infected subjects and by ingestion of contaminated food and drinks (WHO 1995). Since HAV circulation is diminished but not eliminated, both large epidemics (like the one registered in 1996–97 in Puglia, Italy) (Malfait et al 1996;Lopalco et al 2005) or more limited outbreaks (frequently starting in schools or day-care centers) can occur.
HAV Vaccine
All of the hepatitis A vaccines are highly immunogenic and efficacious. Approximately 97 to 100% of children, adolescents, and adults develop protective antibody levels within 1 month of the first dose of vaccine. Essentially 100% of vaccines develop high antibody titres after completing the 2-dose series, with long-term persistence of protective antibody levels 10 years out from vaccination. In randomized double-blind placebo-controlled trials, 94-100% children were protected against clinical hepatitis A after receiving the equivalent of a single dose.
Here is a picture that shows the Groups recommended for Hepatitis A Vaccine
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