Zoster virus vaccine

Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.

Zostavax (Merck Sharp & Dohme)
vials containing lyophilised virus for reconstitution
Approved indication: prevention of herpes zoster infection
Australian Medicines Handbook section 20.1

Herpes zoster (shingles) results from a reactivation of varicella zoster virus, which primarily causes chickenpox. Shingles is characterised by a painful blistering skin rash. Over half of all cases involve people over 60 years of age as viral reactivation is associated with waning cellular immunity.

Complications associated with herpes zoster are common. From June 1999 to July 2000, there were 1918 admissions to Australian hospitals due to herpes zoster; 1142 of these patients had complications.¹ The most frequent complication is postherpetic neuralgia, a painful condition which can persist for years and diminish the quality of life.

The vaccine, which has been registered in Australia, is a live attenuated strain of varicella zoster virus. It is to be given as a single subcutaneous dose.

The safety and efficacy of the vaccine have been assessed in a single placebo-controlled trial of 36 716 adults aged 60 years or older in the USA. Most of the participants (95%) were actively followed for three years after vaccination for signs of herpes zoster. There were 642 confirmed cases of herpes zoster in 18 357 control patients compared with only 315 confirmed cases in 18 359 vaccinated patients. The median duration of pain was 21 days in the vaccine group compared with 24 days in the control group. Similarly, the severity of disease was less in the vaccine group compared to the control group. There were 107 cases of postherpetic neuralgia; 27 in the vaccine group and 80 in the placebo group.²

The numbers of deaths and serious adverse events were similar in the vaccine and control groups. Safety was more closely monitored for 42 days following injection in a sub-group of 6616 people. In the vaccine group, 1604 people (48%) had at least one adverse event at the injection site compared with 539 people (16%) in the placebo group. Systemic adverse events related to the intervention were more frequently reported by vaccinated individuals than by people who received the placebo (209 vs 160).²

People for whom the vaccine is not recommended include:

• immuno deficient patients or patients on immunosuppressive therapy, such as high-dose corticosteroids
• patients with a history of anaphylaxis to neomycin
• patients with untreated tuberculosis.

There is a theoretical risk that the vaccine virus could be transmitted from a vaccinated person, who has developed a varicella-like rash, to a susceptible contact.

Although this vaccine will decrease the incidence of herpes zoster, its efficacy is only around 51%. Its duration of protection beyond four years is unknown, so it is unclear if people will need to be revaccinated.

Most of the efficacy data for this vaccine are from people aged 60 years or over. However, the vaccine has also been approved for individuals aged 50–59 based on immunogenicity data alone.

manufacturer provided only the product information

The Transparency Score () is explained in New drugs: transparency', Vol 37 No 1, Aust Prescr 2014;37:27.

Notes on references

At the time the comment was prepared, information about this drug was available on the web site of the Food and Drug Administration in the USA (www.fda.gov).

At the time the comment was prepared, a scientific discussion about this drug was available on the website of the European Medicines Agency (www.emea.europa.eu).