Zostavax contains a live attenuated form of the varicella zoster virus, specifically the Oka/Merck strain, at a concentration of at least 19,400 plaque forming units (PFU) per 0.65ml dose. Given as a single subcutaneous injection in the upper arm, it is licensed to prevent future occurrences of shingles and can also be given to patients with shingles to prevent recurrence.1
The vaccine is only available on private prescription. Although GPs are able to issue and administer Zostavax as part of their NHS work, patients must pay for it privately at a pharmacy.
A large, double-blind placebo-controlled trial involving 38,546 patients over 60 years old evaluated the potential of the Oka/Merck varicella zoster virus vaccine to reduce the burden of illness caused by herpes zoster.2
Patients received a single dose of the trial vaccine, median potency 24,600 PFU (range 18,700 to 60,000 PFU) per dose, or placebo, and were then monitored monthly for signs of herpes zoster infection. Surveillance continued for a median of 3.12 years).2
Over 95% of patients completed the study. At study completion, 957 cases of herpes zoster were confirmed: 315 in the treatment arm compared with 642 in the placebo group. Analysis indicated that use of the vaccine reduced the burden of illness caused by herpes zoster by 61.1%, and the incidence of post-herpetic neuralgia and herpes zoster by 66.5% and 51.3% respectively (p<0.001 for all three comparisons).2
The vaccine was generally well tolerated although headache and injection site reactions, including localised varicella-like rashes, were observed more commonly in the treatment arm than in the placebo group.1,2
Further Information: Sanofi Pasteur MSD
Updated 12 June 2012
Zostavax now available on NHS prescription
From 3 May 2012, Zostavax can be prescribed and administered on the NHS.