FDA recommends nucleic acid testing to reduce HBV transmission

January 11, 2016

The FDA issued a draft guidance recommending the use of FDA-licensed hepatitis B virus infection nucleic acid tests for donors of human cells, tissues and cellular and tissue-based products in an effort to reduce the transmission of infection.

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The draft guidance, when finalized, will represent the current thinking of the FDA on HBV, according to the guidance, and is a supplement to previous recommendations from the FDA in 2007 which were given to establishments that provide human cells, tissues and cellular and tissue-based products (HCT/Ps).

“The FDA-licensed HBV [nucleic acid test] can detect evidence of the viral infection at an earlier stage than the hepatitis B surface antigen and total antibody to hepatitis B core antigen tests,” the FDA wrote in its guidance. “Therefore, we recommend the use of FDA-licensed HBV [nucleic acid tests], in addition to the use of licensed [hepatitis B surface antigen] and [total antibody to hepatitis B core antigen] immunoglobulin G and immunoglobulin M, for testing donors of HCT/Ps for evidence of infection with HBV.”

According to the guidance, adding HBV nucleic acid testing (NAT) for HBV reduces the residual risk of transmission of HBV beyond screening donors for only hepatitis B surface antigen (HBsAg) and total antibody to hepatitis B core antigen (anti-HBc) tests because HBV NAT is more sensitive in the detection of HBV DNA.

“It can detect breakthrough infections in previously vaccinated individuals who are exposed to the virus, and HBV mutants appear to be more likely detected by HBV NAT than by HBsAg assays,” the FDA wrote.

The guidance further stated that HBV viremia at tissue donation is higher compared with probability of viremia in first-time blood donors — 1 in 34,000 — and HBV NAT testing could reduce this number.

“It was estimated that the probability of donor viremia could be reduced to 1 in 100,000 if HBV NAT individual testing were used. Therefore, by analogy to the experience in the blood donor setting, it is reasonable to expect that the residual risk of transmission of HBV infection would be reduced by adding HBV NAT to the testing strategy for HCT/P donors,” the guidance said.

There are multiplex assays currently available that simultaneously check HIV, HCV and HBV in blood, according to the guidance, and improve the “feasibility of routine NAT testing for HBV.”

The FDA estimates that between 700,000 and 1.4 million people in the U.S. have HBV, many of whom are not aware they have the infection