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) Center, completed last Friday
by the Beijing Red Cross Blood Center, could go a long way towards
raising the country's standard of blood safety and alleviating some
of those worries.
The center was built in cooperation 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-center 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
centers, said Ren Furong, director of blood transfusion safety
laboratory with the Beijing Red Cross Blood Center.
"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
centers 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-center trial," said Zhang Ping, deputy director of the
Beijing Red Cross Blood Center.
Six blood centers across China have joined the trial program.
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 centers 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 Tumor Hospital.
The hospital retests each unit of blood to cut down the chance
of transfusion-transmitted infections.
"Blood transfusion cannot be 100 percent safe. Our clinical
principle is to avoid any unnecessary blood transfusions and reduce
the transfusion amount as much as we can," said Zhao.
(China Daily November 13, 2003)