Cytomegalovirus (CMV) IgG Avidity Test

The Cytomegalovirus (CMV) IgG Avidity Test is a specialised blood test used to help determine whether a CMV infection was acquired recently or in the more distant past. It is particularly valuable for pregnant women, immunocompromised individuals, and anyone whose CMV IgG antibody result is positive but the timing of infection is unclear. By measuring the strength with which CMV-specific IgG antibodies bind to the virus, this test provides a reliable indication of infection timing, which is crucial for clinical management and counselling.

What the test measures
- Cytomegalovirus (CMV) IgG Avidity: This test measures the avidity (binding strength) of CMV-specific IgG antibodies. Low avidity suggests a recent primary infection (typically within the last 3 months), while high avidity indicates a past infection (usually more than 3 months ago). The result is reported as an avidity index or percentage, helping clinicians interpret the likelihood of recent infection.

Why it matters
CMV is a common virus that can cause serious complications in certain groups. In pregnancy, primary CMV infection can lead to congenital CMV, which may result in hearing loss, developmental delays, and other health issues. For immunocompromised patients, such as transplant recipients or those with HIV, knowing whether CMV infection is recent or remote guides monitoring and treatment decisions. The IgG avidity test provides essential information that helps doctors assess risk, plan appropriate care, and offer accurate advice, ultimately supporting better outcomes for vulnerable patients.

• Cytomegalovirus (CMV) IgG Avidity

No special preparation required.

For blood tests, we recommend drinking plenty of water beforehand to ensure smooth sample collection. If you are taking any regular medication, continue to do so unless advised otherwise by your doctor.