New test method helps reduce blood safety fears
( 2003-11-13 09:09) (China Daily)
Newer testing methods may help curb the spread of infectious diseases through blood transfusions.
The prevalence of diseases such as AIDS and hepatitis B and C, is making both doctors and patients increasingly concerned over the safety of blood transfusions.
A new Nucleic Acid Testing (NAT) Centre, completed last Friday by the Beijing Red Cross Blood Centre, could go a long way towards raising the country's standard of blood safety and alleviating some of those worries.
The centre was built in co-operation with the United States-based Chiron.
"What we are trying to do is to help train Chinese scientists in transfusion medicine on the latest technology for blood screening," said Jack Goldstein, Ph.D. and president of Chiron's Blood Testing Division.
"We are going to begin a multi-centre NAT trial in conjunction with John Hopkins University in order to look at the residual risk of HIV and hepatitis in blood donors, to compare the results of NAT with that of the routine serology test."
In the 1980s, blood was screened using serology technology, which measured the number of antibodies created in the blood to combat HIV or HBV viruses.
However, it takes time for the body to build those antibodies, weeks or even months, leaving a "window period."
During this period, transfusions of infected blood could occur.
In China, traditional serology tests are still in use in blood centres, said Ren Furong, director of blood transfusion safety laboratory with the Beijing Red Cross Blood Centre.
"Though very rarely, clinical cases of blood transfusion infection still happen after the blood is tested by the serology method," she said.
By comparison, in the developed countries of America and Europe, as well as Japan, Australia, New Zealand and Singapore, blood centres use state-of-the-art NAT technology to test for the viruses themselves.
NAT significantly shortens the "window period" and increases the level of safety of donated blood supplies.
Goldstein added: "In theory, NAT will add an important layer of safety to China's blood supply, for it is much more sensitive than the traditional method in window phase."
"However, we are still waiting for the final data from the multi-centre trial," said Zhang Ping, deputy director of the Beijing Red Cross Blood Centre.
Six blood centres across China have joined the trial programme. They are located in Beijing, Guangzhou in South China's Guangdong Province, Chengdu in Southwest China's Sichuan Province, Kunming in Southwest China's Yunnan Province, as well as Urumqi and the construction corps in Northwest China's Xinjiang Uygur Autonomous Region.
Blood samples from those centres will be sent to the NAT lab, where scientists will do both serology and NAT on the blood samples to determine how many samples would test positive by the latter while not by the former.
"The results will be used for reference by the Ministry of Health on its policy on blood safety," said doctor Zhang.
While acknowledging what the new NAT technology will bring, Chinese medical doctors fear a considerable increase in the costs of blood transfusion. Higher costs may inhibit the spread of the new NAT testing.
In Western countries, it costs around US$10 to NAT-test each unit of blood, said Goldstein.
"It will cost a lot of money to screen blood for transfusions if we add the new test, but the chances of missing viruses will be reduced. The government will weigh the advantages and disadvantages (in formulating the new test standards)," said Ren.
She believed a mandatory NAT test of source plasma would likely be enforced earlier than that of blood.
Still, patients' awareness of blood transfusion safety is growing stronger and stronger.
"Most (people) in need of a blood transfusion demand more tests of the blood, though they would pay an extra bill for it. After doing that, they feel safer," said Zhao Weiqi, a doctor at the blood bank in the Beijing Tumour Hospital.
The hospital retests each unit of blood to cut down the chance of transfusion-transmitted infections.
"Blood transfusion cannot be 100 per cent safe. Our clinical principle is to avoid any unnecessary blood transfusions and reduce the transfusion amount as much as we can," said Zhao.
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