As a late complication of VZV infection, Ramsay Hunt syndrome type 2 may develop in rare cases.

Even when clinical symptoms of chickenpox have resolved, VZV remains dormant in the nervous system of the infected person (virus latency), in the trigeminal and dorsal root ganglia.

[10] Shingles lesions and the associated pain, often described as burning, tend to occur on the skin that is innervated by one or two adjacent sensory nerves, almost always on one side of the body only.

In Ramsay Hunt syndrome, VZV affects the geniculate ganglion giving lesions that follow specific branches of the facial nerve.

Symptoms may include painful blisters on the tongue and ear along with one-sided facial weakness and hearing loss.

Reye's syndrome can happen after initial infection, causing continuous vomiting and signs of brain dysfunction such as extreme drowsiness or combative behavior.

VZV also fails to produce the LAT (latency-associated transcripts) that play an important role in establishing HSV latency (herpes simplex virus).

Their lipid envelope encloses the 100 nm nucleocapsid of 162 hexameric and pentameric capsomeres arranged in an icosahedral form.

The tegument is in turn covered by a lipid envelope studded with glycoproteins that are displayed on the exterior of the virion, each approximately 8 nm long.

Practically all molecular epidemiological data on global VZV strains distribution are obtained with targeted sequencing of selected regions.

Phylogenetic analysis of VZV genomic sequences resolves wild-type strains into nine genotypes (E1, E2, J, M1, M2, M3, M4, VIII and IX).

Sequence analysis of 342 clinical varicella and zoster specimens from 18 European countries identified the following distribution of VZV genotypes: E1, 221 (65%); E2, 87 (25%); M1, 20 (6%); M2, 3 (1%); M4, 11 (3%).

[20] Within the human body it can be treated by a number of drugs and therapeutic agents including acyclovir for chickenpox, famciclovir, valaciclovir for the shingles, zoster-immune globulin (ZIG), and vidarabine.

[21] Acyclovir is frequently used as the drug of choice in primary VZV infections, and beginning its administration early can significantly shorten the duration of any symptoms.

However, reaching an effective serum concentration of acyclovir typically requires intravenous administration, making its use more difficult outside of a hospital.

It was developed by Merck, Sharp & Dohme in the 1980s from the Oka strain virus isolated and attenuated by Michiaki Takahashi and colleagues in the 1970s.

[25] Shingrix is a subunit vaccine (HHV3 glycoprotein E) developed by GlaxoSmithKline which was approved in the United States by the FDA in October 2017.

The word varicella is possibly derived from variola, a term for smallpox coined by Rudolph Augustin Vogel in 1764.