HIV blood screening

The risk of transmitting HIV infection to blood transfusion recipients has been drastically reduced by improved donor selection and sensitive serologic screening assays in many countries. In 2000, WHO estimated that 1 million new HIV infections around the world resulted from inadequate blood screening.

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Screening tests require a high degree of confidence that HIV is not present, so a combination of antibody (serology), antigen and nucleic acid based tests are used by blood banks in Western countries. The average window period with antibody tests is 22 days. Antigen testing cuts the window period to approximately 16 days and NAT further reduces this period to 12 days. FDA 2001

Public demand in the United States for HIV blood screening arose during the campaign to re elect President Ronald Reagan. In April 1984, U.S. Health and Human Services Secretary Margaret Heckler announced to the world at a press conference that an American scientist, Dr. Robert Gallo, had discovered the probable cause of acquired immune deficiency syndrome AIDS: the retrovirus subsequently named Human Immunodeficiency Virus HIV.

The first screening test, an ELISA antibody test, had a high sensitivity but a low specificity. The low specificity of the test is due to cross-reacting antibodies, which attach to HIV particles "by accident", even though the body has never encountered HIV. Antibody tests cannot detect recent HIV infections, because there is a window period of several weeks between infection and the production of antibodies. Antigen and nucleic acid based tests have been introduced in some countries to reduce this window period.

Timeline

• March, 1983 FDA issues donor screening guidelines. AIDS high-risk groups should NOT donate.
• April 23, 1984 Secretary of Health and Human Services Margaret Heckler announces discovery of virus believed to cause AIDS; says test to identify contaminated blood will be available in six months.
• March 2, 1985 FDA approves first HIV antibody screening tests.
• January 14, 1986 "By 1996, three to five million Americans will be HIV positive and one million will be dead of AIDS" - NIAID Director Anthony Fauci, New York Times
• 1987 "By 1990 one in five heterosexuals will be dead of AIDS" - Oprah Winfrey.
• March 14, 1996 Food and Drug Administration (FDA) announced approval of the first antigen test kit to screen blood donors for HIV-1, the virus that is responsible for the vast majority of AIDS cases in the United States.
• September 2, 1997 "The most recent estimate of the number of Americans infected (with HIV), 750,000, is only half the total that government officials used to cite over a decade ago, at a time when experts believed that as many as 1.5 million people carried the virus." article in the Washington Post
• 1997 "There is no recognized standard for establishing the presence or absence of HIV-1 antibody in human blood." (Abbott Labs test kit instructions)
• September 21, 2001 FDA licensed the first nucleic acid test (NAT) systems intended for screening of plasma donors.