Can herpes blood test give false negative


Herpes simplex virus (HSV) is a common, often asymptomatic, viral infection and one of the most commonly sexually transmitted infections. Although there is no cure for herpes, antiviral medications such as acyclovir and valacyclovir can help reduce the severity and duration of symptoms. As such, it is important to diagnose those infected with HSV in order for them to receive appropriate treatment.

There are two types of lab tests that can be used to detect HSV: culture test or polymerase chain reaction (PCR) test also known as ‘swab test’. The culture test involves taking a sample of cells from the affected area. The PCR test involves taking a swab from the affected area in order to detect viral DNA. Both tests may give false negative results: undetectable infection can still be present even if the tests are negative. In addition, HSV-1 is more difficult to detect than HSV-2 by PCR test because lower amounts of virus are shed compared with HSV-2.

Types of herpes blood tests

Herpes blood tests are medical tests that can help detect the presence of the herpes virus in the human body. These tests are an important tool in diagnosing and monitoring the condition of herpes, as they can give information such as type, active infections and current level of immunity.

Several different types of herpes blood tests are available, each of which has its own advantages and disadvantages. Let’s take a look at the different types of herpes blood tests and what they can tell us:

Antibody tests

Antibody tests, which are the most commonly used type of herpes blood test, are designed to identify the presence of antibodies to the herpes virus. This is accomplished by detecting proteins in a sample of blood that have been produced as a result of an immune response to the virus. Antibody tests are generally considered highly accurate. However, it is also possible for antibody tests to give false negative results due to a number of factors.

One potential cause of false negative results is timing. Antibody tests can take up to six weeks after a potential exposure before they show positive results, so if the test is done too soon, it might not detect the antibodies yet even though you may be infected with herpes. Additionally, some individuals may take longer for their body to produce enough antibodies for them to be detectable in a blood test, resulting in false negative results even after six weeks have passed since exposure.

False negative antibody test results can also occur due to other factors such as:

  • Testing on an incorrect sample type (serum instead of plasma)
  • Insufficient sample size
  • Antibody levels that fall just below the cutoff point for being considered positive by the particular antibody test used
  • Technical errors during specimen processing
  • Reporting errors due to human analysis at the laboratory
  • Some individuals simply don’t have enough natural immunity or cannot mount an adequate antibody response if they do have infection; this condition is referred to as “seronegativity” and could lead to false negatives from an antibody test even though an individual may actually be infected with herpes.

Antigen tests

Antigen tests are also called type-specific tests, antigen/antibody tests, or antibody tests. They measure the presence of herpes antigens or proteins in the blood that are directly associated with the virus. These type-specific assays reduce false positives, but can still result in false negatives if the sample is taken too soon after exposure to the virus. Results are usually available in one to three business days and generally do not require specialized equipment or training to complete.

The most common type of antigen test is ELISA (Enzyme-Linked Immunosorbent Assay), which detects immunoglobulin G (IgG). This test is usually used as a part of a diagnosis for genital herpes infections and can detect both types 1 and 2 of the herpes simplex virus (HSV). The ELISA test may result in false negatives around 70% of the time if performed within 12 weeks after exposure to HSV.

If testing does not give you an accurate result, your doctor may order other antigen or antibody tests such as Western Blot or immunofluorescence assay (IFA) to detect HSV antibodies in your blood sample. These lab tests have higher accuracy but take longer for results to come back from when compared with ELISA testing.

Accuracy of herpes blood tests

Herpes blood tests are an effective way to detect the herpes virus in the body, but it is important to be aware of the accuracy of these tests. While herpes blood tests are extremely accurate and reliable, there is a possibility of a false negative result. This article will discuss the accuracy of herpes blood tests, their benefits and drawbacks, and what a false negative result might mean.

False positives

One possible consequence of herpes blood tests is a false positive result. A false positive happens when the test inaccurately identifies a person as having been infected with HSV, even though they have not been.

This type of error is fairly rare but it can still occur if someone’s immunoglobulin (Ig) levels are high or if their sample has been compromised in some way. It could also happen if two different types of testing were conducted and the results were conflicting.

For people concerned about receiving a false positive result from a herpes blood test, it’s important to:

  • Talk to your doctor beforehand about what specific type of test you will be having and how it works so that you can make an informed decision about whether or not to proceed with the testing.
  • Ask for confirmation by another type of test (such as a swab or culture) may be helpful in confirming the results.

False negatives

Herpes blood tests are helpful tools to diagnose herpes infections accurately. However, they can also give false negatives, or negative results that do not reflect the true state of the infection. False negatives occur when the test fails to detect the virus in a person’s body, even when it is present.

False negatives may be due to a number of reasons, including:

  • Insufficient levels of virus particles in a person’s body (such as newly acquired infections).
  • Limitations of test sensitivity; some tests may not pick up low levels of virus particles and hence give false negative results.
  • Lower antibody levels produced by bodies with weakened immune systems; these lower antibody levels may lead to false negative results.
  • Sampling errors; incorrect swabbing or incorrect collection of sample can lead to false negatives if some areas are missed out.

It is important for clinicians and patients alike to understand the limitation of herpes blood tests and be aware of the possibility of false negative results. Depending on the patient’s medical history and clinical symptoms, follow-up testing with other modalities may be necessary in order to obtain more accurate results.

Factors that may affect the accuracy of herpes blood tests

Herpes is one of the most common sexually transmitted infections, and it is highly contagious. Many people who have herpes do not have symptoms and therefore may never get tested. A herpes blood test can help identify the virus, however, it is not always accurate.

Let’s take a look at some factors that may affect the accuracy of the test:

Timing of the test

The timing of the herpes blood test may affect the accuracy of the results. For individuals who have been exposed to HSV-2 in the previous 3 to 4 months, seroconversion (the development of detectable HSV antibodies) may take up to 6 months before being detected in the blood test. During this period, there is a risk that a false negative result might be returned. Therefore, if someone suspects they were recently infected with HSV-2, it is recommended that they get re-tested at least 6 months after their initial test.

It is also important to note that if someone has had HSV-1 or 2 for some time, that it may take longer for the virus to become detectable in a blood sample. This could also lead to false negative results and following up with another test is recommended when this occurs. It is not unusual for a doctor or healthcare provider to request multiple tests over time until an accurate result can be returned.

Finally, it is important to remember that some individuals have weakened immune systems due to underlying illnesses or medications and these people are more likely than others to receive a false negative herpes blood test result due to lower levels of antibodies in response to an infection.

Type of test used

There are two types of blood tests that can be used to verify if a person is infected with the herpes simplex virus (HSV). The first test is called the HSV IgG test which detects antibodies produced by cells in response to the infection. This type of test is more reliable for diagnosing HSV infections, but it may not detect infections that have recently occurred since it takes several weeks for the body to produce a sufficient amount of antibody to be detected on a standard HSV IgG test. The second type of test available is an HSV IgM test, which measures antibodies found in the blood typically within four weeks following infection. This type of blood test may give false negative results unless taken during peak levels.

In addition, sensitivity and specificity vary among different manufacturers and laboratories performing these tests, so it is important to ensure that an appropriate level of accuracy is provided with any herpes testing done. Even after testing positive or negative for herpes via one manufacturer’s kit or lab, obtaining further confirmatory testing from another laboratory can help ensure accurate results. Proper interpretation and use of these tests require clinicians to consider other factors such as clinical presentation and prior serology when making a diagnosis.

Other medical conditions

Apart from the various factors related to the herpes blood test kits and laboratory procedures, some other medical conditions can also potentially affect the accuracy of the results. False negative results may occur in people with compromised immune systems, due to their inability to mount an adequate immune response against herpes antigens present in their body. Autoimmune disorders, including rheumatoid arthritis and lupus, as well as cancer treatment can also weaken the body and consequently, decrease its ability to produce antibodies.

Also, pregnant women have higher levels of immunoglobulin G (IgG), which is a known marker for past infection. In such cases, a false-positive result may emerge due to elevated levels of IgG in the biological sample being tested. This could happen even though an individual is really not infected but has only been exposed to HSV in the past. Additionally, false positive results can occur during acute infection since that stage of herpes doesn’t necessarily involve an adequate amount of antibodies yet for a positive blood test result. As such, healthcare providers should be aware of these medical conditions that may have an impact on herpes diagnosis by blood tests.


In conclusion, herpes antibody tests using blood and other bodily fluids can give false negative results in some cases. This is especially true with early infection as the body has not yet had time to produce enough antibodies to be detected by the test. It is therefore important to speak with a healthcare provider about any potential exposure or symptoms prior to having any testing done.

While these tests are generally accurate, other forms of testing such as genital swabs and PCR tests may still be necessary in certain circumstances.