Explanation

HSV-1/2 IgG (herpes simplex, not split by type): what is measured?

The test looks for IgG antibodies against the herpes simplex virus, without distinguishing between type 1 (HSV-1) and type 2 (HSV-2). HSV-1 usually causes a cold sore, but can also cause genital herpes through oral sex; HSV-2 is almost always in the genital or anal area. IgG antibodies develop weeks to months after the first infection and usually remain present for life, just like the virus itself. Because antibodies against both types are similar, a positive result does not say which type you have, nor where in the body the infection is.

What can it detect?

A past infection with herpes simplex type 1, type 2 or both, even if it never caused symptoms

Result

What does the result mean?

Positive result

A positive result means that you have been infected with HSV-1, HSV-2 or both at some point. This is very common: in a national population study, more than 4 in 10 inhabitants had antibodies against HSV-1, which is often caught at a young age through a cold sore. So the result does not say that you have genital herpes. If you want to know whether it is HSV-2, a type-specific test is needed.

Negative result

A negative result means that no IgG antibodies against herpes simplex have been found. After a first infection, it takes weeks to sometimes months before antibodies can be detected; a recent infection is therefore not ruled out. Even later, an antibody test misses some infections, so a negative result does not give complete certainty.

After an abnormal result

A positive result usually needs no follow-up, because antibodies against herpes simplex are found in many healthy people. If the question is whether you have genital herpes, a doctor can order a type-specific test or, with symptoms, a PCR test on a blister. Herpes is not notifiable.

Reliability

How reliable is the test?

For the question of whether you have genital herpes, this test is of little use: it does not distinguish between HSV-1 and HSV-2, and a large part of the population has HSV-1 antibodies. Blood tests are mainly meaningful with a type-specific test, for example with a partner who has genital herpes or a suspected first infection during pregnancy; this test is not type-specific. With blisters or sores, a PCR test on the fluid from the sore says more, because it detects the virus itself.

What can affect the result?

The test does not distinguish between HSV-1 and HSV-2 and does not say where the infection is (mouth, genitals or skin).
Shortly after a first infection, antibodies cannot yet be detected.
The result says nothing about the moment of infection or about the chance of an outbreak.

Who it is for

Who is the test useful for?

Useful for

The test only shows whether you have ever been in contact with a herpes simplex virus and does not answer the question of whether you have genital herpes. For that question, a type-specific HSV-2 test says more, or with symptoms a PCR test on a blister or sore.

How common is it?

In a national population study (Pienter-2, 2006 to 2007), 42.7 percent of inhabitants had antibodies against HSV-1 and 6 percent against HSV-2; the percentage rises with age. In 2023, GPs made the diagnosis of genital herpes an estimated 28,600 times. The true number of infections is not well known, because most cause no symptoms.

LCI guideline (RIVM) on herpes simplex virus infections (Woestenberg 2016); RIVM

Drawbacks and risks

A positive result can wrongly give the impression that you have genital herpes and cause unnecessary worry.
A negative result shortly after a risk contact can give false reassurance.

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