Zostavax

The Therapeutic Goods Administration (TGA) has published previous safety advice about avoiding the use of Zostavax vaccine in immunocompromised patients but continues to receive reports of such cases. This is a reminder that careful assessment and screening for immunocompromise is essential before administration of Zostavax, with resources to assist in the process.

Background

Zostavax is a live, attenuated varicella zoster virus (VZV) vaccine used to prevent shingles in patients aged 50 years and older, and prevention of nerve pain associated with the virus in patients aged 60 years and older.

All patients for whom Zostavax is considered should be assessed for immunocompromise prior to vaccination. DO NOT administer Zostavax if the immune status of the patient is unclear.

Zostavax is contraindicated in patients with current or recent severe immunocompromising conditions from either a primary or acquired medical condition or medical treatment.

Fatalities due to disseminated disease with vaccine (Oka) strain VZV have followed administration of Zostavax to immunocompromised patients. The risk of disseminated VZV infection with vaccine (Oka) strain increases with the degree of immunosuppression.

Assessing for immunocompromise

Assessing immunocompromise can be complex. A screening checklist - external site to identify patient contraindications prior to vaccination is available in the Australian Immunisation Handbook - external site. Assessment before vaccination can include consulting a medical specialist and screening for pre-existing antibody to VZV. Defer vaccination until advice and results have been obtained.

Other resources for health professionals about using zoster vaccines include:

• Clinical advice: Statement on the use of zoster vaccines in older adults (July 2021) - external site - Australian Technical Advisory Group on Immunisation (ATAGI)
• Zoster vaccines for Australian adults (fact sheet) (pdf,355kb) - external site - National Centre for Immunisation Research and Surveillance (NCIRS)

If inadvertent vaccination in an immunosuppressed patient occurs

An immunosuppressed patient who has been inadvertently vaccinated with Zostavax should be informed of the potential for developing disseminated VZV infection. They should be advised to seek medical advice if the symptoms listed in the 'Information for consumers' below occur, so that they can be considered for pre-emptive antiviral therapy.

Any patient who experiences a disseminated vesicular (chickenpox-like) rash 2 to 4 weeks after vaccine administration, or who feels unwell or has a fever, should seek medical attention immediately and tell the doctor they have received Zostavax.

If disseminated varicella zoster virus infection is suspected

If a recent Zostavax recipient is suspected of having disseminated varicella-zoster virus infection, the health professional should:

• conduct appropriate diagnostic testing early in consultation with a clinical microbiologist or infectious diseases physician
• where appropriate, initiate appropriate empiric antiviral therapy while awaiting test results
• where feasible, cease immunosuppression in consultation with their treating specialist.

Regulatory context and recommended resources

The TGA has received three reports of fatal cases of disseminated VZV infection involving the vaccine (Oka) strain following Zostavax administration. Two of the three deaths arose from medication errors involving the administration of Zostavax to immunocompromised patients. The third death was in an immunocompetent patient.

The TGA has published safety advisories (in March 2017, July 2020 and December 2020) about avoiding the use of Zostavax in people who are immunocompromised and has required the sponsor to undertake several risk mitigation activities including the implementation of multiple new conditions of registration imposed in by the TGA in June 2021.^[1-4]

Despite these activities, the TGA has received five reports of Zostavax administration in immunocompromised patients since 1 July 2021. In all five cases Zostavax was given to patients were subsequently identified to be receiving concurrent immunosuppressive therapies. Neither disseminated VZV infection or death have been reported in any of these cases. Expert advice provided by the Advisory Committee on Vaccines (ACV) on 1 December 2021 acknowledged the main area of difficulty was not likely a lack of awareness that Zostavax should not be given to immunocompromised patients, but rather the complexity of around the assessment and definition of 'immunocompromise'.

About the shingles vaccination program

In October 2021, the Department of Health announced a 2-year extension (to 31 October 2023) of the shingles vaccination catch-up program, which is available under the National Immunisation Program - external site (NIP) for people aged 71 to 79 years.

The TGA has been closely monitoring reports of disseminated vaccine strain varicella zoster infection and has found that the benefits of Zostavax continue to outweigh the risks in the approved population groups.

Information for consumers

Varicella-zoster virus (VZV) is the virus that causes chickenpox and shingles. Infection with varicella-zoster virus can be localised to an area of skin, but can also take a more serious, generalised form that affects a wider area of the body. Widespread infection is called disseminated VZV infection.

Zostavax is a live vaccine and should not be used in people with a weakened immune system, as it can cause serious illness and death from infection with the vaccine virus.

Before you receive Zostavax your doctor should assess whether your immune system could be weakened by any medical conditions you have or medicines you are taking. Tell your doctor if you are taking medicines that may weaken your immune system including high-dose corticosteroids or cancer medicines, or other treatments. Your doctor may also provide a patient safety alert card which details important safety information that you need to be aware of before and after treatment with Zostavax.

If you become unwell after vaccination, you should seek medical attention and tell your doctor that you have recently received Zostavax.

Seek immediate medical attention if you:

• develop a chickenpox-like rash within 2 to 4 weeks of receiving the vaccine
• feel unwell
• develop a fever.

The most common adverse events following Zostavax are reactions at the site of injection, such as redness, pain and swelling. Serious reactions, such as disseminated varicella-zoster virus infection, are very rare.

If you are concerned about whether you or someone you provide care for can receive Zostavax, please speak to your health professional.

For further information about adverse events following Zostavax, you can read the CMI - external site online or ask your doctor or pharmacist for a copy.

Reporting problems

Consumers and health professionals are encouraged to report problems with medicines or vaccines. Your report will contribute to the TGA's monitoring of these products.

The TGA cannot give advice about an individual's medical condition. You are strongly encouraged to talk with a health professional if you are concerned about a possible adverse event associated with a medicine or vaccine.