Zoster (herpes zoster)

What is it?

Herpes zoster (shingles) is caused by a reactivation of the varicella zoster virus (VZV), the same virus that causes varicella (chickenpox) disease. After a person recovers from varicella, the virus stays dormant (inactive) within the dorsal root ganglia of the spinal nerves but can later be reactivated, presenting as zoster. 

What to look for

Zoster is a painful, vesicular (blistering) rash. It usually presents on one side of the face or body, typically appearing in a dermatomal distribution (an area of skin supplied by a spinal nerve). Prior to the emergence of the rash, there is often pain, itching or tingling in the area where the rash will develop. This can happen anywhere from 1 to 5 days before the rash appears. Other symptoms of zoster can include fever, headache, chills and malaise (generally feeling unwell). The vesicles (blisters) typically scab over 7 to 10 days after onset and resolve completely within 2 to 4 weeks. 

Post-herpetic neuralgia (PHN) is the most common complication of zoster and is more likely to occur in older people (> 70 years) than younger people. PHN is a chronic neuropathic (nerve) pain which can affect 1 in 4 cases of zoster diagnosed in those aged > 80 years. It can persist for months or up to several years. Given that pain control for PHN can be difficult to manage, it can impact quality of life. 

Other complications of zoster include skin pigmentation and scarring, secondary bacterial infections, and herpes zoster opthalmicus (eye involvement with differing degrees of symptoms including conjunctivitis, ocular-cranial nerve palsies, loss of vision and debilitating pain). 

How is it transmitted?

Zoster cannot be passed from one person to another. It is the reactivation of an individual’s previous VZV infection. 

Exposure to the fluid-filled vesicles of a zoster rash can result in a VZV infection (as varicella disease) in a seronegative person (a person with no immunity to VZV). Zoster is less contagious than varicella. The risk of a person with zoster spreading the virus is low if the rash is covered. 

Epidemiology

Zoster can only develop in people who have previously been infected with VZV. It more commonly presents in adults aged > 50 years, those who are immunocompromised and those who were diagnosed with a varicella infection at < 12 months. 

The lifetime risk of a reactivation of the VZV virus causing zoster is 20 to 30%. Zoster affects half of all people who live to 80 years. Zoster can present more than once. Repeated presentations occur in 6–8% of immunocompetent people whereas immunocompromised people experience higher rates of repeated presentations. 

Prevention

The only way to reduce the risk of developing zoster is through vaccination. 

There are currently 2 vaccines available in Australia: 

  • Zostavax – a live-attenuated vaccine 
  • Shingrix – an adjuvanted recombinant varicella zoster virus glycoprotein E (gE) subunit (non-live) vaccine. 

Zoster vaccines are not interchangeable with varicella vaccines as they are very different. Zoster vaccines are much more potent than varicella vaccines and are not registered for use in younger people. 

Indications for use

Zostavax is registered for use in adults aged ≥ 50 years and is provided on the National Immunisation Program (NIP) at 70 years of age (with a catch up program for those 71-79 years, ending 31st of October 2023). As it is a live-attenuated vaccine, Zostavax is contraindicated in immunocompromised individuals and pregnant women.

Shingrix is registered for use in immunocompetent adults from ≥ 50 years of age and immunocompromised adults from ≥ 18 years. It is currently only available via a private prescription.

Zostavax

  • Administration

    Immunisation with Zostavax requires a single dose only of 0.65 mL to be administered subcutaneously. It can be co-administered (given on the same day) with other vaccines, including pneumococcal, influenza and COVID-19.

    Zostavax is a live-attenuated vaccine and its use is contraindicated in immunocompromised individuals due to the risk of vaccine-related disease.

  • Efficacy

    Zostavax has been shown to reduce the incidence of zoster by approximately 50% and the incidence of PHN by 66%. 

    Evidence suggests that efficacy decreases with increasing age. Immunogenicity (ability to provoke an immune response) declines rapidly 5 to 10 years after vaccination. 

  • Side effects

    Zostavax has been demonstrated to be safe and well tolerated. Injection site reactions are the most common side effect. A localised varicella-like rash can also occur in the first 72 hours after vaccination. 

    Rarely, a non-localised VZV-like rash can occur 2 to 4 weeks following receipt of Zostavax. Should this occur, medical attention is recommended for advice and management of symptoms which may include diagnostic testing and antiviral treatment. This event must also be reported to the relevant vaccine safety service (SAEFVIC in Victoria). 

  • Contraindications and precautions

    Zostavax is live-attenuated vaccine and is therefore contraindicated in immunocompromised individuals and pregnant women. Prior to administering Zostavax, it is essential to performs pre-immunisation screening of patients with the Australian Immunisation Handbook: Table. Live shingles vaccine (Zostavax) screening for contraindications. 

    If there is uncertainty about how severely a person is immunocompromised and whether it is safe for them to receive a vaccine, do not vaccinate them. Seek expert advice from their treating physician or an immunisation specialist. 

    Find more information regarding the use of Zostavax in people with compromised immune function: 

    TGA: Safety advisory- risk of infection with a vaccine virus. 

  • Inadvertent administration of Zostavax in immunocompromised individuals

    If an immunocompromised patient is inadvertently administered a dose of Zostavax, prompt action is required. Facilitate a medical review by an infectious diseases specialist or immunisation expert, and commence the appropriate anti-viral therapy and monitoring. 

    The error must be reported to the relevant authority to ensure appropriate follow-up and support can be provided. In Victoria, this service is SAEFVIC. 

    If the error occurs out of hours, urgently seek specialist advice from the patient’s treating specialist or an infectious diseases specialist at your local tertiary hospital. 

Shingrix

  • Administration

    Immunisation with Shingrix requires a course of 2-dose course of 0.5 mL given intramuscularly. Doses should be administered 2 to 6 months apart for immune competent individuals aged 50 years and over and 1 to 2 months apart for immunocompromised individuals ≥ 18 years. 

    Shingrix can be co-administered with other vaccines including pneumococcal, influenza and COVID-19 vaccines. 

  • Efficacy

    Shingrix is preferred over Zostavax for the prevention of zoster due to its higher efficacy, particularly in the older population. In those aged ≥ 50 years, Shingrix provides 97% protection against zoster in immunocompetent individuals and 91% protection in those aged > 70 years. 

    Clinical trials demonstrate high efficacy up to 4 years following vaccination. Immunogenicity data indicates that the level of efficacy is likely to persist beyond 10 years. 

  • Side effects

    Expected side effects of Shingrix include injection site reactions, fatigue, myalgia (muscle pain), headaches and fever and last 1 to 3 days. These occur at slightly higher rates than following Zostavax. 

    Following Shingrix administration, an estimated additional 3 to 6 cases of Guillain–Barré syndrome (GBS) per million doses of Shingrix administered have been estimated to occur. 

  • Contraindications and precautions

    Shingrix must not be administered for the treatment of varicella, acute shingles disease or PHN. 

Documentation

It is mandatory to report all NIP vaccinations, including zoster vaccination, to the Australian Immunisation Register (AIR). 

It is important that immunisation records are accurately maintained and reviewed prior to vaccine administration to avoid any dosing errors. Patient recall is not always reliable; it is therefore essential to review an individual’s immunisation history. 

Commonly asked questions

  • Can patients receive Shingrix if they have previously been immunised with Zostavax?

    Yes. A minimum interval of 12 months is recommended between receiving Zostavax and the administration of Shingrix. A 2–dose course of Shingrix is still required. 

  • Can patients receive Zostavax if they have previously received Shingrix?

    No. Zostavax is not recommended for people who have previously received any zoster vaccine. 

  • Should patients with a clinical history of zoster receive zoster vaccines?

    Yes. People can experience zoster more than once in a lifetime. Approximately 6 to 8% of immunocompetent people will have a repeat episode of zoster within 8 years of their first diagnosis. Further episodes are even more common for individuals with immune compromise. 

    Immunocompetent individuals should wait at least 12 months following a zoster diagnosis before receiving an age-appropriate zoster vaccine (either Shingrix or Zostavax). In the first 12 months after infection, the risk of a further episode is low. 

    Immunocompromised individuals are at an increased risk of further episode of zoster compared with immune competent people. It is recommended that they receive a 2-dose course of Shingrix a minimum of 3 months after acute illness. 

Resources

Authors: Nigel Crawford (Director, SAEFVIC, Murdoch Children’s Research Institute) and Georgina Lewis (Clinical manager, SAEFVIC, Murdoch Children’s Research Institute)

Reviewed by: Rachael McGuire (MVEC Education Nurse Coordinator)

Date: August 24, 2023

Materials in this section are updated as new information and vaccines become available. The Melbourne Vaccine Education Centre (MVEC) staff regularly reviews materials for accuracy.

You should not consider the information in this site to be specific, professional medical advice for your personal health or for your family’s personal health. For medical concerns, including decisions about vaccinations, medications and other treatments, you should always consult a healthcare professional.

by Rachael McGuire