February 24, 2022

Tri dot test window period

TRI DOT test; HIV TRI DOT & HCV TRI DOT are screening tests for the qualitative detection of HIV & HCV antibodies, respectively, in Human serum and Plasma.

In individuals infected with HIV, the p24 antigen appears first before anti-HIV. However, due to seroconversion, the antigen is lost. Thereby the antibody develops within 1-2 months after infection, and thereby, the level of the antibody increases. The antigen can generally be detected in the acute phase and during the symptomatic phase of AIDS. The antibodies can be seen throughout the infection.

The window period is the time period between infection and the development of detectable antibodies or antigens in the patient serum/Plasma. The window period for a test is defined as when the test can show an accurate result. As per CDC guidelines, the window period of HIV infection is 18-45 days for the test performed on serum/Plasma.


The window period of HIV TRI DOT is 30-60 days & the window period of HCV is 8 to 11 weeks. HIV TRI DOT & HCV TRI DOT are 99% accurate within the defined window period. However, they may not detect the respective HIV/HCV antibodies in the patient sample if the patient is suffering from some other infections with low immunity or in the early seroconversion phase of the disease.

HIV TRI DOT is the rapid visual test for the differential detection of HIV-1 & HIV-2 antibodies in Human serum /Plasma. The product is standardized using envelope antigens ; gp 41 & gp120 against HIV-1 & gp36 HIV-2 . The antibodies against envelope antigens are developed first and remain throughout the infection, thus ensuring the detection of HIV infection in the seroconversion stage of the infection.

HCV TRI DOT is a 4th generation, rapid visual test for HCV antibodies in Human serum /Plasma. Since the product is developed and designed with increased sensitivity for core and NS3 antibodies using a unique combination of modified HCV antigens; Core, NS3, NS4 & NS5, the accuracy in test results is ensured concerning sensitivity and specificity.

The product performance of both HIV TRI DOT & HCV TRI DOT has been evaluated using seroconversion panels and low antibody titer panels by WHO with 100% Sensitivity & Specificity (HIV) & 98.9%(HCV). In addition, the products have also been evaluated by various Govt. referral institutes /centers against CLIA /ELISA as reference methods and are approved for use in Blood banks.

It is advised to do repeat testing after 30-60 days if a patient sample is in the window period and is detected negative by TRI DOT.

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