Blood infected with hepatitis B was transfused to over 100 people, due to a delay by the Korea Red Cross in using the latest testing methods, data showed Monday.

According to the Korea Centers for Disease Control and Prevention, those who tested positive for hepatitis B after a new testing method was introduced by the Red Cross in May last year had their blood previously offered for transfusion retested.

Data showed that in 59 cases, the blood had erroneously been tested negative and accordingly had been transfused to 117 people.

The data from the center was made public by Rep. Kim Yong-ik of the Democratic United Party, who is a member of the National Assembly Health and Welfare Committee.

According to an investigation by the health authorities, two of the 117 have not been infected by the transfusion and testing is ongoing for the remaining 115.

The errors were detected as the blood was retested using the Nucleic Acid Amplification Test (NAT).

NAT confirms the genes of pathogens and is able to detect early infections, something the enzyme immunoassay (EIA) method that is currently used does not. The “window period” which refers to the initial time period for which people with hepatitis B do not test positive is 59 days for EIA while for NAT it is 25 days.

Rep. Kim pointed out that it is highly likely that more cases undetected by the current testing method will surface as NAT continues to be employed.

As Korea has a relatively large number of people with hepatitis B, the need for NAT had previously been suggested but the Korean Red Cross only started running the new test in June last year.

“Due to the Red Cross’ delay in utilizing the latest testing method, a large number of patients have ended up receiving infected blood,” said Kim. “Health authorities must track down those who have been infected by transfusions.”

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