Transmission of hepatitis A through household contact

Abstract

In the USA, cost effectiveness assessments support childhood hepatitis A vaccination in geographical areas with elevated disease rates, but not nationally. However, these studies do not address the reduction in disease transmission which may result from routine childhood vaccination. Using decision analysis, we estimated the number and age distribution of secondary hepatitis A cases occurring within households with an index case. Based on the age of the index case, we determined household size and age composition, the proportion of household members susceptible to hepatitis A, the probability of disease transmission, and the likelihood secondarily infected household members would exhibit symptoms. Our model indicates that for every 100 index cases age 6-11 years, 47.2 secondary infections would occur within households, with 23.1 causing overt disease. Lower transmission rates for older index cases reflect smaller household sizes and a higher proportion of household contacts with hepatitis A immunity. When disease transmission rates are applied to a model simulating lifetime risks of hepatitis A, universal vaccination of an annual USA birth cohort is estimated to prevent 24 100 cases of overt disease among household contacts in addition to 71 000 cases among vaccinees. Sensitivity analysis provides a wide range of estimates, but even conservative assumptions suggest routine vaccination would yield an important reduction in secondary cases. Evaluations of hepatitis A prevention should consider the ability of immunization to protect household and other personal contacts.

Cost-effectiveness of childhood hepatitis A vaccination in Argentina: a second dose is warranted

“…However, the 12-and 18-month regimen would offer approximately twice the reduction in cases, deaths, and lost QALYs among personal contacts. This is entirely due to increased vaccine protection between ages 18 and 71 months, when viral transmission most commonly occurs (33).…”

“…The model predicts the number of secondary cases resulting from personal contact with individuals infected with hepatitis A based on household size, age distribution, and age-specific probabilities of having hepatitis A immunity. In the United States, each 100 hepatitis A infections are predicted to result in 13.7 to 23.1 other intrahousehold cases, depending on age of the index infection (33). In Argentina, predicted rates of secondary cases are similar in low endemicity areas, but considerably less in other regions due to higher rates of immunity among household contacts (Table 1).…”

Incidence of Hepatitis A in Israel Following Universal Immunization of Toddlers

“…Epidemiologic studies demonstrate that toddlers are the main distributors of hepatitis A virus in the community. 10,11,33,34 Although most children in this age group are susceptible to infection, they are often asymptomatic during infection and excrete hepatitis A virus for up to several months. 30,34,35 Our findings suggest that if high vaccine coverage is achieved in toddlers, a catch-up effort in other ages may not be needed.…”

The cost-effectiveness of universal vaccination of children against hepatitis A in Argentina: results of a dynamic health–economic analysis

“…5,6 Although treatment protocols and supportive care reduce the impact of symptomatic disease, transmission of hepatitis A virus into the environment and among children during asymptomatic infections remains a major challenge to reducing the burden of hepatitis A disease. [6][7][8][9][10] Vaccination is a proven method for preventing the spread of infection as well as controlling outbreaks, both directly by reducing transmission of the virus, and indirectly by establishing herd immunity. [11][12][13][14][15][16][17][18][19] The impact of herd immunity on levels of symptomatic hepatitis A has been demonstrated in Israel, where the immunization of children has decreased rates of symptomatic disease among adults within a few years.…”