The Incidence of Hepatitis A Infection
How common is Hepatitis A infection?
Hepatitis A incidence varies between regions and is much more common in countries with underdeveloped sanitation systems; thus, contracting hepatitis A is a risk in most of the world. An increased transmission rate is seen in all countries other than the United States, Canada, Japan, Australia, New Zealand, and the countries of Western Europe. Infections continue to occur in the United States.
Each year, approximately 3,700 to 10,000 cases of hepatitis A occur in the United States. Historically, acute hepatitis A rates have varied cyclically, with nationwide increases every 10 to 15 years. Although the national incidence—0.4 cases per 100,000 population, or 1,239 cases—of hepatitis A was the lowest ever recorded in 2014, it is estimated that asymptomatic infections and underreporting kept the documented incidence rate lower than it actually is. In fact, it is estimated that there were 3,500 infections in 2014.
The national rate of HAV infections declined steadily between 1995 and 2014 after vaccines for hepatitis A were licensed in 1995 and 1996. Unfortunately, cases began to increase in 2016 and 2017. The increase was primarily due to emerging outbreaks in several states among persons using injection and non-injection drugs, persons experiencing homelessness, and persons currently or recently incarcerated.
Although the rates of HAV infection have declined over the years, they are twice as high among American Indians and Alaskan Natives. Hispanics are also twice as likely to be infected compared to non-Hispanic Whites in the United States. Rates among American Indians and Alaskan Natives have decreased dramatically, largely as a result of increased vaccination of children in both urban and rural communities.
In 2016, the CDC reported a total of 2,007 acute symptomatic cases of hepatitis A. Of these, information about food and water exposure was known for 796 cases, leading to an estimate that 19.7% of all infections were caused by exposure to contaminated water or food. In 612 of the cases, no known risk factor was identified, and in 918 of the cases, risk factor information was not reported to CDC.
Estimates of the annual costs (direct and indirect) of hepatitis A in the United States have ranged from $300 million to $488.8 million in 1997 dollars. In one study conducted in Spokane, Washington, the combined direct and indirect costs for each case of hepatitis A from all sources ranged from $2,892 to $3,837. In a 2007 Ohio study, each case of HAV infection attributable to contaminated food was estimated to cost at least $10,000, including medical and other non-economic costs. A 2020 study found that the average cost of a hepatitis A hospitalization in 2017 was $16,232. Nationwide, adults who become ill miss an average of 27 workdays per illness, and 11 to 22 percent of those infected are hospitalized. All of these costs are entirely preventable given the effectiveness of a vaccination in providing immunity from infection.