There is only one virus that causes shingles: varicella-zoster virus, also known as human herpesvirus type 3. If you’ve seen references to different “types” of shingles, those refer either to the genetic variations within this single virus species or to the different ways shingles can appear on the body depending on which nerve it affects. The virus itself is always the same one.
One Virus, Two Diseases
Varicella-zoster virus causes two distinct illnesses at different points in your life. The first time you’re infected, usually in childhood, it causes chickenpox. After that infection clears, the virus doesn’t leave your body. It retreats into nerve cells near the spine and brain, where it can remain dormant for decades.
When the virus reactivates later in life, it travels along a nerve fiber to the skin and produces the painful, blistering rash known as shingles. About 1 in 3 people in the United States will develop shingles at some point. The reactivation is thought to happen when the immune system weakens, whether from aging, stress, illness, or medications that suppress immune function. At the cellular level, the virus is kept in check by specific signaling pathways in neurons. When those pathways are disrupted, the virus begins replicating again and moves toward the skin surface.
Genetic Clades of the Virus
While there’s only one species of varicella-zoster virus, scientists have identified genetic variations within it. Full-genome sequencing has confirmed five major clades (numbered 1 through 5), plus two provisional clades (VI and VII) that still need further confirmation. These clades are essentially geographic family trees of the virus.
Specific clades tend to dominate in certain parts of the world, likely influenced by evolutionary history, climate differences between temperate and tropical regions, and migration patterns that carry particular strains across borders. For you as a patient, though, these genetic differences don’t change much. All clades cause the same two diseases, chickenpox and shingles, and all respond to the same treatments and vaccines. The clade distinction matters mainly to researchers tracking how the virus has spread and evolved globally.
Where Shingles Is Not the Same as Other Herpesviruses
Part of the confusion around “types” comes from the fact that varicella-zoster virus belongs to a larger family. Eight different herpesviruses infect humans, and several of them cause skin blisters that can look similar at first glance.
- Herpes simplex virus type 1 typically causes cold sores around the mouth.
- Herpes simplex virus type 2 is the primary cause of genital herpes.
- Varicella-zoster virus (type 3) causes chickenpox and shingles.
- Epstein-Barr virus (type 4) causes mononucleosis and is linked to certain cancers.
- Cytomegalovirus (type 5) can cause serious infections in newborns and immunocompromised people.
- Human herpesviruses 6 and 7 cause roseola, a common childhood rash.
- Human herpesvirus 8 is associated with Kaposi sarcoma in people with weakened immune systems.
Only type 3 causes shingles. Herpes simplex types 1 and 2 can produce blisters that look somewhat similar, but the pattern is different. Shingles almost always appears in a band or strip on one side of the body, following the path of a single nerve. That distinctive one-sided rash is often enough for a doctor to diagnose it on sight, though a PCR test (which detects viral DNA from a skin swab) is the most reliable confirmation when the presentation is unusual.
Clinical Forms of Shingles
The same virus can produce different clinical pictures depending on which nerve is affected. These aren’t different types of the virus. They’re different locations where the same virus reactivates.
The most common form is a painful rash wrapping around one side of the torso, following the path of a nerve that branches from the spine. When the virus reactivates in a nerve serving the face, specifically the first branch of the trigeminal nerve, it causes herpes zoster ophthalmicus. This form affects the forehead and can involve the eye, potentially leading to corneal scarring, glaucoma, or vision loss. A telling sign is a lesion on the tip of the nose, called Hutchinson’s sign, which indicates a threefold higher risk of eye involvement.
Shingles can also affect the ear and facial nerve, causing ear pain, hearing changes, and sometimes facial paralysis. In rare cases, the virus reactivates in more than one nerve region simultaneously, or it can spread more widely in people with severely weakened immune systems. Regardless of location, the underlying virus is identical.
What Vaccination Changes
Because a single virus is responsible for all cases of shingles, one vaccine covers everything. The current recombinant vaccine is over 90% effective at preventing shingles in adults 50 and older with healthy immune systems. In adults aged 50 to 69, effectiveness reaches 97%. For those 70 and older, it drops slightly to 91% but remains high. Protection lasts at least seven years in people over 70, and the vaccine is also 89% to 91% effective at preventing postherpetic neuralgia, the lingering nerve pain that can persist for months after the rash heals.
For people with weakened immune systems, effectiveness ranges from 68% to 91% depending on the specific condition involved. The vaccine works by training the immune system to recognize proteins from varicella-zoster virus, reinforcing the body’s ability to keep the dormant virus suppressed in nerve cells.