In the United States, Hepatitis A is a frequently reported vaccine-preventable disease.
Vaccination has been recommended for persons at increased risk since 1996.
In 1999, it was recommended that children living in 11 states with the highest incidence of Hepatitis A be routinely vaccinated.
It was also recommended that children living in 6 additional states, with incidence above the national average, be considered for routine vaccination.
Dr Annemarie Wasley and colleagues assessed the impact of the current vaccination strategy.
The research team evaluated trends in reported cases of Hepatitis A since implementation.
|Hep A declined 88% in vaccinating states compared with 53% elsewhere|
|Journal of the American Medical Association|
The team conducted a longitudinal analysis of characteristics of cases of Hepatitis A.
The researchers included all cases reported in the United States since 1990 to the National Notifiable Diseases Surveillance System.
The main outcome measure was the incidence rates of reported cases of Hepatitis A.
Incidence rates in 2003 were compared with those for the prevaccination baseline period from 1990 to 1997.
The researchers also compared incidence rates in the 17 states in which children should be routinely vaccinated or are considered for routine vaccination.
Incidence rates in vaccinating states were also compared with nonvaccinating states, where there is no recommendation for statewide vaccination of children.
The team found that between the baseline period and 2003, overall Hepatitis A rates declined 76%, significantly lower than previous nadirs in 1983 and 1992.
The researchers noted that the rate in vaccinating states declined 88% compared with 53% elsewhere.
In 2003, the team observed that cases from vaccinating states accounted for 33% of the national total versus 65% during the baseline period.
Declines were greater among children aged 2 to 18 years than among persons older than age 18 years.
The researchers found that the proportion of cases in children dropped from 35% to 19%.
Since 2001, the team noted that rates in adults have been higher than among children, with the highest rates now among men aged 25 through 39 years.
Dr Wasley's team concludes, “Following implementation of routine Hepatitis A vaccination of children, Hepatitis A rates have declined to historic lows.”
“This decline is accompanied by substantial changes in the epidemiologic profile.”
“Greater decreases in the age groups and regions where routine vaccination of children is recommended likely reflect the results of implementation of this novel vaccination strategy.”
“Continued monitoring is needed to verify that implementation continues to proceed and that low rates are sustained. “