One-year ID-NAT screening of 732,250 donations interdicted 16 HIV, 20 HBV, and 1 HCV window phase donations and 42 anti-hepatitis B core antigen-reactive infections during an early recovery or a later stage of occult HBV infection.

The implementation of enhanced education and selection policies in South Africa was associated with decreased prevalence of HIV-1 in blood donations.

Assuming the mean window period from first HBV viraemia to HBsAg positivity is 38·3 days, the mean window period from first HBV viraemia to ID NAT positivity is 8·3 days. The HBV incidence was measured by adjusting the HBsAg seroconversion rates with a factor of 2·38 (see Methods). b Assuming the mean window period from ID-NAT positivity to HBsAg positivity is 30 days. NE: The residual risk and projected yield was not estimated because of a lack of information on the incidence rates of HBV in first-time donors.