However, the mechanism is unclear and mortality from cancer did not appear to increase as a direct result of the presence of the virus. Instead, the increased risk may result from the immune suppression that allows the reactivation of the virus.Although shingles typically resolves within 3–5 weeks, certain complications may arise:

Secondary bacterial infection. Motor involvement, including weakness especially in "motor herpes zoster". Eye involvement: trigeminal nerve involvement (as seen in herpes ophthalmicus) should be treated early and aggressively as it may lead to blindness. Involvement of the tip of the nose in the zoster rash is a strong predictor of herpes ophthalmicus. Postherpetic neuralgia, a condition of chronic pain following shingles. Epidemiology
Varicella zoster virus (VZV) has a high level of infectivity and has a worldwide prevalence. Shingles is a re-activation of latent VZV infection: zoster can only occur in someone who has previously had chickenpox (varicella). Shingles has no relationship to season and does not occur in epidemics. There is, however, a strong relationship with increasing age. The incidence rate of shingles ranges from 1.2 to 3.4 per 1,000 person‐years among younger healthy individuals, increasing to 3.9–11.8 per 1,000 person‐years among those older than 65 years, and incidence rates worldwide are similar. This relationship with age has been demonstrated in many countries, and is attributed to the fact that cellular immunity declines as people grow older. Another important risk factor is immunosuppression. Other risk factors include psychological stress.
They include a live attenuated virus vaccine, Zostavax, and an adjuvanted subunit vaccine, Shingrix.A review by Cochrane concluded that Zostavax was useful for preventing shingles for at least three years. This equates to about 50% relative risk reduction. The vaccine reduced rates of persistent, severe pain after shingles by 66% in people who contracted shingles despite vaccination. Vaccine efficacy was maintained through four years of follow up. It has been recommended that people with primary or acquired immunodeficiency should not receive the live vaccine.Two doses of Shingrix are recommended, which provide about 90% protection at 3.5 years. As of 2016, it had been studied only in people with an intact immune system. It appears to also be effective in the very old.In the UK, shingles vaccination is offered by the National Health Service (NHS) to all people in their 70s. As of 2021 Zostavax is the usual vaccine, but Shingrix vaccine is recommended if Zostavax is unsuitable, for example for those with immune system issues. Vaccination is not available to people over 80 as "it seems to be less effective in this age group". By August 2017, just under half of eligible 70–78 year olds had been vaccinated. About 3% of those eligible by age have conditions that suppress their immune system, and should not receive Zostavax. There had been 1,104 adverse reaction reports by April 2018. In the US, it is recommended that healthy adults 50 years and older receive two doses of Shingrix, two to six months apart.