Herpes blood tests have a sensitivity level of about 80-98%. This type of test detects antibodies to the herpes virus, so it may not be as accurate when performed soon after infection. In general, false positives are a concern with herpes testing, so it’s not recommended unless you have symptoms or have a high risk for infection.
Blood Test Basics
Herpes blood tests, also known as herpes serologic tests, are available for both types of the virus (HSV-1 and HSV-2). Type-specific glycoprotein G-based serologic tests are designed to detect whether there are any antibodies to the herpes virus in the blood. Blood tests have a sensitivity of about 80-98% for HSV-2.
If antibodies for HSV-2 are present, it’s a genital infection. HSV-1 is very common in the population and antibodies for this type of herpes typically indicate an oral infection. However, there’s a small chance of getting an HSV-1 genital infection and the test cannot distinguish where the infection is located.
False negatives are not common with this type of test, but there’s still a chance that a negative result for HSV-1 or HSV-2 may not be accurate depending on the timing of your exposure. Since it takes the body some time to develop antibodies to the virus, the results may be negative if you are tested soon after becoming infected.
False positives are a concern with herpes blood tests. A false positive result is possible with any diagnostic test, but researchers worry that the outcome of a false positive for herpes may be particularly damaging since it is a lifelong infection.
Due to the concern over false positives, these blood tests are only recommended for people with herpes symptoms and those who have a higher risk for infection, such as people who have a partner with genital herpes.