Why Aren't We All Screened for Herpes?

The real-world limits of current tests, and what you should know before asking to be "tested for everything"

Many people are often frustrated that a test for herpes wasn’t included when they asked to be screened for “everything” for sexually transmitted infections (STI) and are shocked to hear that universal screening (testing everyone without symptoms) isn’t recommended. Before discussing the ins and outs of screening tests, I first wanted to review the basics about herpes, which I did in my previous post that you can find here. Now, let’s get to the issues with screening tests, which hopefully will explain why universal screening is not recommended.

Screening Tests: The Basics

A screening test involves testing people with no signs of symptoms of a medical condition, and several things need to be true for the screening test to be of value. The test should:

1) Accurately detect a meaningful proportion of people with the condition. Some tests are just so inaccurate they should not even be considered. A good example of a bad test is thermography for breast cancer screening, as the false negative rate (the chance of missing cancers) is atrociously high. Tests with a high false negative rate risk erroneously telling people they don’t have the condition, when they do. While thermography is just useless (and any provider recommending it should be a red flag for a scammer and/or someone who is medically illiterate), some tests are appropriate when the risk of a condition is higher, but not so much when the risk is lower, so this also needs to be considered. For example, assume a test for chlamydia has a false positive rate of 2%, that’s sounds pretty good, unless we’re testing people at very low risk, say a population where less that 1% of people are expected to test positive. In this situation the likelihood of a false positive is greater than a true positive, and so the test isn’t very useful.

2) Has a benefit, meaning the test provides useful information that, when acted upon, improves health. For example, we have data that shows screening people with a cervix who are age 24 and younger for chlamydia allows us to treat those who test positive, which has been shown to reduce the risk of pelvic inflammatory disease. Conditions that we screen for are usually significant enough that if left untreated serious harm is the end result, for example, chlamydia and pelvic inflammatory disease, or screening for breast cancer or colon cancer as earlier diagnoses improve outcomes.

3) Have screening benefits that outweigh the harm. The harm with screening tests can be too many false positives or false negatives. False positives can lead to worry and often further testing that can even sometimes be invasive.

4) Be theoretically possible to get everyone access to a screening test who qualifies.

A screening test for herpes can’t be a genital swab, because people only shed the virus intermittently. The only option is a blood test for type-specific IgG antibodies, meaning one that can accurately distinguish between antibodies (evidence of prior infection) for HSV-1 and HSV-2. Type-specific antibodies develop anywhere from 3 weeks to 16 weeks after infection.

Screening for HSV-1

Screening people without symptoms for HSV-1 is of no value in identifying people with genital herpes, because the test does not tell you the location of the infection. If the test is positive the infection could be oral or genital. In addition, most genital infections with HSV-1 have fewer recurrences, so the consequences are less.

The most common test that detects the antibody for HSV-1 is also not that accurate. In a study from 2017 (more detailed information on that study below) tells us that:

• 91.7% of people who test positive for HSV-1 antibodies are truly positive

• 70% of people who tested negative for HSV-1 antibodies are truly negative

This means the test can miss a significant number of people who are positive. There are some newer tests, but they still have performance issues.

Screening for HSV-2

The most used test in the United States, HerpeSelect enzyme immunoassay (EIA, the test mentioned above), also performs poorly as screening test for HSV-2 in the general population. We know this because in the study I referenced above, researchers looked at how this test performed as a screen for herpes against a Western Blot, which is the gold standard (but also relatively expensive and not easily accessible). The results are not great:

• 50.7% of people who tested positive for HSV-2 antibodies were truly positive; this means almost 50% of people who were told they were positive were in fact negative!

• 93.7% of people who tested negative for HSV-2 were truly negative; this means 6.3% of people who were told they were negative, were positive.

Usually, a result over 1.0 on this radioimmunoassay is considered positive, although a value of 1.1 to 2.9 is considered a low positive. The investigators looked at the low positive vs high positive (≥ 3.0) results for HSV-2:

• 39.8% of people who tested low positive for HSV-2 antibodies were truly positive

• 78.6% of people who tested high positive for HSV-2 antibodies were truly positive

This means the regular antibody tests performs poorly as a screen for HSV-2; if someone tests negative there’s a pretty good chance, they are negative, but if they test positive there is still a pretty good chance they could really be negative.

The recommendation from the CDC (this predates RFK Jr) and from other experts is that when someone tests positive for HSV-2 antibodies in a screening test using a commercially available test that they should have the result confirmed with a second test, either a Biokit or Western Blot. Not every lab offers the BioKit (although it’s easy to do and relatively inexpensive, but only available for HSV-2) and the Western Blot is expensive and in the United States is only available at one lab and it takes some arranging (it is about $282.00 for the test plus the cost of the lab drawing the blood and the cost of overnight shipping the specimen on ice to Seattle; also, there are situations where doing the test twice is indicated, doubling the cost). This additional layer of testing affects the universal accessibility of the test. If the follow-up testing isn’t available for a positive result or can’t be done, there is little point to the test because a positive result without a confirmatory testing is hard to interpret.

Newer Data is Available, but It’s Still Not Great for Screening

A newer study (2024, so published after the CDC and the USPSFT guidelines) in a very experienced lab looked at three different blood tests for herpes antibodies (tests from DiaSorin, Roche, and Bio-Rad.) These tests are FDA 510(k) cleared for use in the United States. While the Roche test performed the best, there were still false positives. The investigators considered that if the general population had a 12% prevalence of HSV-2 (which it about what it is in the United States) and if 100,000 people were tested the false positives would be follow:

• Roche, 440 people, although there were no false positives for people who were negative for both HSV-1 and HSV-2 by Western Blot.

• Bio-Rad 1,672 people

• DiaSorin 5,104 people

The authors of this newer paper state that the currently available tests for herpes “have limitations precluding widespread use for HSV-1 and HSV-2 testing,” and that their data “support the CDC’s currently recommended two-tiered algorithm for confirming HSV serological diagnoses.”

What if I Still Want to Be Screened for Genital Herpes?

As previously discussed, if you test positive for HSV-1 it doesn’t help you know if you have had genital herpes, because the test can’t distinguish between genital or oral.

If you test positive for HSV-2 on any blood test besides a Western Blot, you need a strategy for a second confirmatory test or you must be okay with accepting that a positive result may not be accurate (which kind of defeats the purpose of the test). A BioKit is inexpensive and something a lab should be able to arrange but should and can or will are different things. The other option is a Western Blot which is more expensive and will take some effort on your part to make happen. There is information about arranging a Western Blot here.

The reality of testing the general population for herpes is that the commercial tests are not that reliable, and they risk telling enough people that they have herpes when they do not, and so a second testing is needed and that test may not be easily accessible. This disqualifies the currently widely available blood tests for herpes from being useful as a screening test. As genital herpes doesn’t pose a significant health risk for most people, it’s hard to know how a universal screening program would offer a significant benefit, although admittedly, as we don’t have a good screening test for HSV-2, it’s not even possible to evaluate the potential benefits of a screening program.

With screening for herpes in the general population there is a level of complexity and ambiguity that we don’t see with screening for other STIs, like chlamydia. It’s not wrong for an individual to want to be tested, but it’s important to accept the many imitations, which is probably the best summary of the reason why universal screening for herpes is not recommended.

References

US Preventive Services Task Force; Mangione CM, Barry MJ, Nicholson WK, Cabana M, Chelmow D, Coker TR, Davis EM, Donahue KE, Jaén CR, Kubik M, Li L, Ogedegbe G, Pbert L, Ruiz JM, Stevermer J, Wong JB. Serologic Screening for Genital Herpes Infection: US Preventive Services Task Force Reaffirmation Recommendation Statement. JAMA. 2023 Feb 14;329(6):502-507. doi: 10.1001/jama.2023.0057. PMID: 36786784.

FDA warning re false positive HSV tests. Accessed June 24, 2025 https://www.fda.gov/medical-devices/letters-health-care-providers/hsv-2-tests-genital-herpes-can-produce-false-reactive-results-letter-clinical-laboratory-staff-and

Agyemang E, Le QA, Warren T, et al. Performance of commercial enzyme-linked immunoassays for diagnosis of herpes simplex virus-1 and herpes simplex virus-2 infection in a clinical setting. Sex Transm Dis 2017;44:763–7.

Crawford KHD, Selke S, Pepper G, Goecker E, Sobel A, Wald A, Johnston C, Greninger AL. 2024. Performance characteristics of highly automated HSV-1 and HSV-2 IgG testing. J Clin Microbiol 62:e00263-24.

American Sexual Health Association https://www.ashasexualhealth.org/new-research-highlights-need-improved-herpes-diagnostics/

Van Wagoner N, Qushair F, Johnston C. Genital Herpes Infection: Progress and Problems. Infect Dis Clin North Am. 2023 Jun;37(2):351-367. doi: 10.1016/j.idc.2023.02.011. PMID: 37105647.

CDC STI Guidelines (I checked and nothing has changed, so still reliable for now). https://www.cdc.gov/std/treatment-guidelines/herpes.htm