Universal vaccination has nearly eliminated hepatitis A among all age groups in Alaska, according to a study presented at the World Indigenous Peoples’ Conference on Viral Hepatitis.
“Dramatic declines in the incidence of hepatitis A occurred after HAV vaccine was recommended as a routine childhood vaccine and after it was required for school entry,” the researchers reported in a press release. “Prior to routine vaccination, most [of] the reported HAV cases were associated with outbreaks occurring within Alaska. Since 2008 however, 88% of reported hepatitis A cases have been imported, many of which were acquired during travel outside of the United States.”
To control increasing rates of HAV among Alaskan citizens, especially the disproportionately high rates among Alaska Natives, the Alaska Section of Epidemiology implemented universal HAV vaccination with state-supplied vaccines for all children aged 2 years to 14 years in January 1996. Prior to this, the average yearly incidence of HAV in Alaska was 60 per 100,000 persons with the average among Alaska Natives as high as 243.8 per 100,000 between 1972 and 1995.
The first widespread use of HAV vaccine was between 1993 and 1994. General population HAV incidence rates decreased from 134.9 per 100,000 in 1993 to 8.5 in 1995, while the rates decreased from 748 per 100,000 in 1993 to 13.4 in 1995 among Alaska Natives.
Vaccination became a requirement for school entry in Alaska in 2001. From this point, the researchers found a 98.4% decrease in HAV among all age groups of Alaskans from 60 per 100,000 prior to vaccine licensure to 0.9 between 2002 and 2007. Similarly, for the Alaska Natives, the rate decreased to 0.3 per 100,000 in 2002 and 0.7 per 100,000 in 2007 (RR = 0.54; 95% CI, 0.36-1.25).
Between 2002 and 2007, the Alaska Section of Epidemiology received 34 reports of HAV infection. The researchers estimate that if the rates from prior to vaccine licensure had continued, there would have been 2,086 cases.
Alaska Native tribal facilities documented HAV vaccination among their child population (ages 2 to 18 years) from their electronic databases in June 2002. Of 52,821 Alaska Native children, 65% had evidence of one or more HAV vaccination. In 2008, the coverage for 2 doses of HAV vaccine among 11,242 adolescent Alaska Native children between ages 11 years and 17 years was 94% within 3 years.
Prior to universal vaccination in Alaska, most cases of HAV were correlated with endemic outbreaks within the state; however, since 2001, 71.4% of HAV cases have been “imported,” likely due to travel outside of the U.S.
“Since HAV transmission has been nearly eliminated in Alaska, universal vaccination has resulted in a shift in continued HAV infections from community-wide outbreaks to uncommon sporadic cases, primarily acquired outside of Alaska and the United States, and rare food-borne outbreaks,” the researchers wrote. “The risk of such imported cases is growing in the United States because of increased travel of U.S. citizens to endemic areas, importation of food from other countries, and adoption of children from endemic countries. The continued occurrence of HAV cases, which are now mostly imported, is a reason to remain vigilant with surveillance and to maintain a strong immunization program.” – by Talitha Bennett
Disclosure: Healio.com/Hepatology was unable to determine relevant financial disclosures of the other researchers at the time of publication.