Shingrix to replace Zostavax on the National Immunisation Program
November 20, 2023
Shingrix a welcomed advancement
The landscape of immunisation is ever-evolving, with constant advancements and updates to ensure optimal public health. In a significant leap forward, Australia’s National Immunisation Program (NIP) is set to introduce the recombinant zoster vaccine (RZV), known commercially as Shingrix, replacing the less potent Zostavax. This change comes with a hefty government funding of $446.5 million, underscoring the commitment to tackle herpes zoster (HZ) infections more effectively. However, the transition is not without its complexities, particularly regarding who gets access to this enhanced protection.
Shingrix’s superiority over Zostavax stems from its recombinant technology, offering heightened immunity, especially among older adults – a group notoriously susceptible to the varicella-zoster virus’s complications. Previously, access to Shingrix was limited to private prescription, a barrier removed by its inclusion in the NIP. Still, despite its proven efficacy, eligibility restrictions have raised concerns within the medical community.
The limitations of Zostavax
The Therapeutic Goods Administration (TGA) highlighted critical concerns regarding the Zostavax vaccine, reporting three instances of fatal disseminated Varicella Zoster Virus (VZV) infections linked to the vaccine strain. Particularly alarming was the fact that two of these fatalities involved immunocompromised individuals incorrectly given Zostavax due to medication errors. Additionally, one death occurred in a patient with a competent immune system.
In response to these incidents, the TGA issued several public safety advisories from 2017 to 2020, explicitly cautioning against the use of Zostavax in individuals with compromised immune systems. Moreover, they mandated the vaccine’s sponsor to initiate risk mitigation strategies, resulting in new conditions for the vaccine’s registration introduced in June 2021.
However, despite these precautionary measures, there have been five additional incidents since July 2021 where Zostavax was inappropriately administered to patients on immunosuppressive treatments. Fortunately, these cases did not lead to disseminated VZV infection or death. On analysing these incidents, the Advisory Committee on Vaccines (ACV) emphasised on December 1, 2021, that the issue does not appear to stem from a lack of understanding regarding the vaccines contraindicated in immunocompromised patients. Instead, the problem lies in the intricate nature of evaluating and categorising ‘immunocompromise,’ which complicates the safe administration of Zostavax. This complexity underscores the need for clear, accessible guidelines and heightened vigilance in patient assessment prior to Zostavax administration.
Shingrix, the choice of the PBAC
The Pharmaceutical Benefits Advisory Committee (PBAC) recommended Shingrix for specific demographics: non-Indigenous individuals at the milestone age of 70, Aboriginal and Torres Strait Islander individuals 50 years and above, and immunocompromised individuals 18 years and older. These categories align with those at elevated risk for severe HZ infections. Notably, the vaccine’s reach does not extend to non-Indigenous individuals aged 65–69 or those 71 and above, labelled as “lower clinical priority” due to cost considerations and the extensive volume of doses required.
Dr. Rod Pearce, a general practitioner and Chair of the Immunisation Coalition, voices notable disappointment with these limitations. The vaccine, efficacious even a decade after administration, seems unjustly restricted, potentially sidelining individuals 71 and older who remain highly susceptible to HZ complications. This sentiment highlights a larger issue: the delicate balance between medical necessity, cost-effectiveness, and national budget allocation.
Moreover, the definition of “high risk” for HZ infection demands clarity. As Dr. Pearce stresses, the current categorisation encompasses various health statuses, treatments, and conditions compromising the immune system. This broad and somewhat vague definition complicates clinical decision-making, potentially leading to gaps in immunisation among those who need it most.
The PBAC shares these concerns, seeking further insights from the Australian Technical Advisory Group on Immunisation (ATAGI) to refine these criteria. The goal is to ensure that Shingrix reaches a broader, yet appropriately targeted, population of immunocompromised individuals for whom the vaccine is both clinically beneficial and cost-effective.
As the medical community awaits more detailed guidelines, there’s an acknowledgment of the necessity for this transition in the immunisation program. The introduction of Shingrix and other vaccines, like the 15-valent pneumococcal conjugate vaccine (Vaxneuvance), signifies a commitment to enhanced, more inclusive public health strategies.
The challenge lies in fine-tuning eligibility criteria to ensure those most at risk receive vital immunisation. As the NIP evolves, continuous dialogue among healthcare professionals, advisory committees, and public health policymakers is essential to navigate these changes effectively, balancing economic constraints with the population’s healthcare needs.
In conclusion, the change to Shingrix in the immunisation space is a welcome advancement. However, it brings to the forefront critical discussions about vaccine accessibility, priority setting, and the importance of clear, evidence-based guidelines to ensure that the most vulnerable populations are not overlooked in the quest for broader public health protection.