How prevalent is HBV?
In Southeast Asia, China, and sub-Saharan Africa, HBV infection usually is acquired perinatally or in early childhood, leading to a high prevalence of chronic infection (5 to 20 percent). Because newborns have an immature immune system, 90 percent of infants infected perinatally progress to chronic infection. Progression to chronic HBV infection occurs in 25 to 30 percent of persons infected before five years of age, and in 3 to 5 percent of those infected later in childhood or as adults. Immuno-suppressed patients are at greater risk of becoming chronically infected.
