An avidity test measures the antibody binding force, which is low in the early stage after the primary infection, but generally increases with time. High avidity means that the infection is likely to have occured at least 4 months earlier. The test result is low, in acute phase, high in chronic phase of infection. Therefore, the test is useful to distinguish the primary infection from the past infection.
Interpretation:The presence of IgM test cannot be used to diagnose primary infection, because IgM can also be present during secondary infection. IgM positive results in combination with low IgG avidity results, are reliable evidence for primary (present) infection. Following primary infection, IgG antibodies have low binding strength (low avidity) than over 2-4 months of mature infection (high avidity).
Sample: Arm vein blood. Nonfasting
Working day: Everyday
Result Time: Next day 6:00 PM
