Protecting Patient and Public Health
Serious viral diseases like HIV or Hepatitis can be transfused to patients from infected units of blood. Some blood donors with very early stage viral infections may not even be aware that they are infected. This is why blood banks screen donated blood for viral and other infectious diseases before the blood is released for medical use. Laboratory screening helps detect infected units of blood so that they can be removed from the blood supply1.
One donor can infect many people
A single unit of blood can benefit many patients. Depending on how blood is separated into different therapeutic components (such as red blood cells…), a single unit of blood could be used to treat from 1 to 5 recipients.
Two types of tests help protect the blood supply from infectious diseases. The first tests developed to screen donated blood for infectious disease, known as serology tests (or immunoassays), detect antigens and the antibodies that a person's immune system creates in response to a viral infection. Although serology plays a major role in protecting blood supplies, this technology is better at detecting later-stage (more established) infections.
Later, as biotechnology discoveries and associated technologies advanced, a more recent type of highly sensitive testing called "NAT" (nucleic acid testing) was introduced. NAT is different from serology testing because it detects the genetic material of the virus itself, rather than signs of the body's immune response to infection. NAT is highly sensitive, giving labs the ability to detect as few as a single copy of the genetic material in a donor's sample.
The Value of NAT
By detecting the RNA or DNA of the virus itself, NAT can identify very low level viral infections that immunoassays may miss. This is helpful for narrowing what experts call the "infectious window period" – that is, the time between infection and when that infection can be detected with a laboratory test. By shortening this "window period," NAT can help make the blood supply safer for patients who depend upon donated blood for their care2.
NAT in combination with serology is an infectious disease screening standard used by many blood banks around the world - especially as automation and software have increased NAT's overall ease of use. Many countries have noted the positive impact on public health following the implementation of NAT blood screening, including countries with high disease prevalence and incidence3.
1. Current safety of the blood supply in the United States, Dodd Int J Hemaol. 2004 November; 80 (4): 301-5.
2. Risks of Blood Transfusion, Goodnough, Lawrence T, Anesthesiology Clinics of North America. 2005 June; 23 (2): 241-252.