In vitro diagnostics (IVDs) are tests that can detect disease, conditions and infections. In vitro simply means ‘in glass’, meaning these tests are typically conducted in test tubes and similar equipment, as opposed to in vivo tests, which are conducted in the body itself. In vitro tests may be done in laboratories, health care facilities or even in the home. The tests themselves can be performed on a variety of instruments ranging from small, handheld tests to complex laboratory instruments. They allow doctors to diagnose patients effectively and work to provide appropriate treatments.
Diagnosis is a driver of patient, financial and health systems impact, and a critical enabler of universal health coverage, but it is also the weakest link in the care cascade. This is especially true in primary healthcare settings in low- and middle-income countries. These countries often lack an integrated network of laboratories used for such diagnosis; however, broad set of IVDs is available for testing patients in the primary care setting where laboratories are not available.
Over 40 000 products are available today for in vitro diagnostic testing, covering a wide range of conditions. These include traditional laboratory-based tests, with samples being sent to a central laboratory for analysis, and point-of-care tests, which can be performed near, or at, the point of patient care. Point-of-care testing can help optimize treatment decision-making, avoid referrals, improve the efficiency of care and decrease costs, especially in resource-constrained settings where laboratory infrastructure is weak.
Diagnostic tests are increasingly important around the world as a first defence against the spread of many diseases. The fight against tuberculosis, for example, replies on modern diagnostics as a prerequisite for the early, rapid and accurate detection of the disease and changes in drug resistance used in its treatment.
In vitro diagnostics are also the first line of defence against the possibility of the re-emergence of eradicated diseases. Smallpox, for example, is unlikely to reappear; however, WHO maintains a network of partnerships around the world dedicated to the rapid diagnosis and containment of any potential cases.
Access to good quality, affordable, and appropriate health products is indispensable to advance universal health coverage, address health emergencies, and promote healthier populations – the three strategic priorities of the World Health Organization (WHO) Thirteenth General Programme of Work 2019–2023.
To ensure the quality of diagnosis for priority diseases, the WHO prequalification team evaluates the safety and performance of a number of diagnostic tests according to international standards. Tests found to meet the required criteria are listed on a public web site and eligible for procurement by UN and international procurement agencies. Countries may also use the prequalification list to purchase diagnostics.
The WHO procurement service for in vitro diagnostics was established in 1990 to facilitate Member States' access to high quality HIV test kits at a reasonable cost. Over the years, the service has expanded to include diagnostics for HIV/AIDS, malaria, hepatitis B and hepatitis C, as well as basic laboratory consumables and equipment.
The WHO also develops and updates the WHO Model List of Essential in vitro Diagnostics (EDL), a list of recommended in vitro diagnostic tests (IVDs) for point of care in the community and for laboratory, that should be available in every country. The EDL provides guidance based on the latest evidence, to countries for creating or updating their national lists of essential IVDs.