Hepatitis A is caused by a picorna-virus with six genotypes but only one serotype.
Hepatitis A-virus is spread via person-to person-contact, by water or by food.
Thus, countries with poor hygiene and sanitation have highest incidences of infection and young children play a major role as source of the infection.
Infection with HAV produces life-long immunity to re-infection.
Exposure to hepatitis A-virus may result in asymptomatic infection (frequent in children), in «classical» icteric disease, or in fulminant disease, which may result in death. While there is a plethora of complications, overall, these are infrequent.
There is no specific treatment.
Passive immunization with human immunoglobulin before or early after exposure reduces the frequency for symptomatic infection.
There are several inactivated vaccines available world-wide.
Even following a single dose only, immunogenicity of these vaccines is high; however, a second dose is routinely given and may provide improved long-term immunogenicity.
Protection rates in clinical trials were 94-100%.
While the duration of protection following vaccination is not yet known, observations and mathematical modelling of antibody persistence suggest that protection may persist at least 25 years.
After a dose of a hepatitis A vaccine, local and systemic reactions occur frequently, but they are mild and acceptable.
Routine use of hepatitis A vaccine has been highly efficacious in decreasing incidences of the disease.