Additional test implemented for Hep B

Hep B anti-core

25 January 2023

Hepatitis B virus (HBV) is one of several viruses that can cause inflammation of the liver (hepatitis), and sometimes liver damage. 

Hepatitis B is very common in many parts of the world, where it may be transmitted from mother to child at birth or acquired in infancy. Donors who have chronic hepatitis B are likely to have acquired their infection in childhood or early life. 

Until recently we carried out two screening tests for hepatitis B; one looking for a marker called hepatitis B surface antigen, which is part of the ‘coat’ of the virus; the second looking for the virus itself, targeting the virus nucleic acid (NAT). Since the introduction of NAT screening we have started to identify donors with occult hepatitis B, where no surface antigen is detected but nucleic acid is detected, however, this nucleic acid may be at very low levels, potentially below the level of detection of our tests. 

The Advisory Committee on the Safety of Blood, Tissues and Organs has recently reviewed current screening practices for hepatitis B in blood donations particularly looking at those donors with occult hepatitis B infection and has made recommendations on additional testing methods. 

It was recommended that a third test for hepatitis B, a test for hepatitis B anti-core should be introduced which will identify donors with past hepatitis B.  The third test was introduced from 31 May 2022 and is gradually being rolled out. 

Occult hepatitis B infection, as defined by the UK blood services, are those donors who have markers to anti-core and hepatitis B DNA. If we find surface antigen and/or the virus nucleic acid in a donor’s blood then further tests are performed to confirm the result. As with all tests some donors may have non-specific reactions to these tests.  

We expect that only a small number of donors will have had previous Hepatitis B infection, however, these donors will no longer be eligible to donate.

The UK has one of the safest blood supplies in the world – there is less than one in a million chance of current screening tests missing a newly acquired infection. We are committed to continually improving standards through regular reviews of the latest science and epidemiology of viruses and diseases and make changes where needed. 

Dr Su Brailsford
Consultant in Epidemiology and Health Protection
Interim Clinical Director Microbiology and Public Health
Honorary Professor, University of Nottingham