The inclusion of Zostavax on the National Immunisation Program in 2016 led to a reduction in herpes zoster rates, but not in immunocompromised individuals, a study has shown.

Using antiviral prescription rates as a proxy for changes in herpes zoster incidence, researchers at  Melbourne University showed that a rising trend in zoster prior to 2016 was reversed following the introduction of free vaccine for the over 70 age group.

Their analysis of PBS data (link here) showed that in the years prior to widespread use of the live attenuated zoster vaccine, prescription rates for antivirals such as acyclovir, valaciclovir and famiciclovir increased 2.6-fold between 1995 and 2015, from 25.4 to 65.3 prescriptions per 10,000 people, respectively.

Since November 2016, the Australian National Immunisation Program (NIP) has provided free Zostavax vaccination for individuals aged 70 and a catch up program for individuals aged 71–79 years.

PBS data showed that between 2016 and 2018 the rates of zoster antiviral prescribing decreased 55% from 60.9 to 27.5 prescriptions per 10,000 people.

However, there was a continuing increase in the prescription rate for the antiviral famciclovir indication restricted specifically for treating zoster in immunocompromised individuals.

Prescription rates increased 8.5-fold between 2006 (when it was first listed) and 2019, from 0.3 to 2.5  prescriptions per 10,000 people.

The famciclovir prescription rate continued to increase even after the introduction of Zostavax on the NIP between 2016 and 2019, rising from 1.9 to 2.5 prescriptions per 10,000 people.

The researchers said the overall reduction in zoster antiviral prescriptions after 2016 was in line with findings from two other Australian studies that showed a reduced HZ incidence in the post-Zostavax era.

Being a live vaccine that is contraindicated for people who are immunocompromised due to disease or medical treatment, it was not unexpected to see a continuing rise in zoster incidence among immunocompromised individuals, they added.

The authors suggested that the introduction of the non-live subunit zoster vaccine Shingrix – which is approved for use in immunocompromised individuals – may lead to a similar reduction in zoster incidence as seen in the general population with Zostavax vaccination.

“The recent availability of Shingrix in Australia may lead to a further reduction in HZ antiviral prescriptions, especially as it is the preferred vaccine for those aged > 50 years and the immunocompromised,” they wrote.

“However, Shingrix’s potential benefit may be limited if it remains accessible via private prescription only and not via Australia’s National Immunisation Program,” they added.

The findings are published in Infectious Disease and Therapy. The authors declare no conflict of interest