Western Blot sensitivity specificity.

[Frank303]

There's been a lot of discussion on the sensitivity of Antibody tests.

What about the Western Blot confirmatory tests.
If they were run without ELISA (I know they aren't but just to look at WB independently)
Are they sensitive?
Does their sensitivity change over time after exposure?
Would they detect infections within the 3 month?

[regularjoey]

HIV Western Blots have slightly lower sensitivity, but higher specificity than ELISAs.  The window period for the WB is usually a little longer than for the ELISA.  False positive Western Blots are extremely rare.

[alienshadow]

western blot is suppose to be used to confirm hiv infection
after an elisa test or rapid test then they usually test on the elisa one more time to make sure it wasnt a false positive if positive then they confirm with the wb

[Frank303]

Could the slightly longer window period of the WB over the ELISA be why the 3 month window period remains despite shorter Ab detection times in ELISAs?
After all they don't diagnose from ELISA alone.

[alienshadow]

elisa is a cheaper test thats why it comes first then if positive they follow up one more time elisa then wb to confirm it if both test are positive then you most certainly have hiv

[Teak]

There is no slightly longer window period for the Western Blot.

[regularjoey]

Western Blot usually takes a little longer to turn positive than the ELISA.
For that reason, if the ELISA is positive, but the Western Blot is negative or indeterminate, another follow-up test is recommended 1 month later.

[Teak]

At 3 months it doesn't matter which test is taken and 3 months is when on can a conclusive negative results. So no the Western Blot would not take a little longer to show a positive.

[Teak]

At 3 months it doesn't matter which test is taken and 3 months is when on can a conclusive negative results. So no the Western Blot would not take a little longer to show a positive.