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Universal HAV vaccine protects children in Argentina up to 9 years
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Children aged 1 year in Argentina experienced sustained immunologic protection up to 9 years after receiving a single-dose of a universal hepatitis A virus vaccine, according to published findings.
“Since 2005 and up to 2013 … more than 6 million doses of HAV vaccine were applied in the country and national vaccine coverage was above 92% during the whole period,” Analía Urueña, MD, of the National Vaccine-Preventable Diseases Control Program, Ministry of Health, Argentina, and colleagues wrote. “Universal vaccination at 1 year against HAV has led … Argentina to an impressive decline in the burden of the disease, as evidenced by the decline in reported cases and incidence rates, as well as the absence of HAV-associated liver transplants since March 2007.”
Universal single-dose HAV vaccination was initiated in Argentina in 2005 after a nationwide outbreak occurred in 2003 and 2004. To continuously assess long-term seroprotection against HAV after vaccination, Urueña and colleagues evaluated 1,088 children from five clinical centers in 2013 and 2014 who received one dose of HAV vaccine at age 1 year and at least 6 years before enrollment. Blood samples were tested for anti-HAV antibodies, with any values of at least 10 mIU/mL indicating seroprotection. Among the children, the median post-vaccination interval was 7.7 years.
The researchers determined that 97.4% of the children (95% CI, 96.3-98.3) had protective antibodies against HAV. Four children had HAV antibody levels greater than 30,000 mIU/mL, which possibly “represented breakthrough infections.” They said, however, they could not confirm that as anti-HAV IgM antibodies were not measured, and none of the children reportedly had the infection or contact with someone with the infection.
Multivariate analysis showed no association between children and mother’s demographic or socioeconomic variables and the number of children with seroprotection.
The geometric mean concentration of antibody levels against HAV was 170.5 mIU/mL (95% CI, 163.2-178.2).
The researchers noted that they were unable to correlate the rate of seroprotection among the patients with vaccine type because different HAV vaccine trademarks were used and data were not recorded.
“Argentina has been a pioneer in the implementation of this strategy and other countries in the region have also followed the SAGE 2012 recommendation and adopted a similar policy,” Urueña and colleagues wrote. “We believe that local and periodic seroprevalence studies are vital to give support to this recommendation, as well as constant passive and active surveillance is crucial to monitor the effectiveness of this innovative strategy.” – by Melinda Stevens
Disclosure: The researchers report no relevant financial disclosures.
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