Summary of the National Advisory Committee on Immunization (NACI) Statement: Updated recommendations on herpes zoster vaccination for adults who are immunocompromised.

Background: Herpes zoster (HZ), or shingles, results from the reactivation of latent varicella-zoster virus and poses a significant health burden and immunocompromised adults are at higher risk of HZ and its complications. In 2018, the recombinant zoster vaccine (RZV, Shingrix®) was strongly recommended by the National Advisory Committee on Immunization (NACI) for immunocompetent adults aged 50 years and older. Since then, evidence has accumulated on the use of RZV in immunocompromised adults and in 2021, Health Canada expanded the authorization of RZV to adults 18 years of age and older who are or will be immunocompromised. Methods: NACI assessed the burden of HZ in immunocompromised populations, reviewed evidence on the efficacy, effectiveness, immunogenicity and safety of RZV, and published economic evaluations. Programmatic considerations were evaluated using NACI's ethics, equity, feasibility and acceptability framework. The evidence and programmatic considerations were organized using a process informed by the Results: The risk of HZ among younger adults who are immunocompromised is comparable to or higher than the general population of 50 years of age and older. High efficacy and robust immune responses after RZV administration was demonstrated in groups with various types of immunocompromising therapies and conditions, with an acceptable safety profile. Economic evaluations showed that RZV was cost-effective in some high-risk immunocompromised groups. Expanding access to RZV may reduce disease burden and address inequities in vaccine access. Conclusion: NACI updated its guidance to strongly recommend that individuals 18 years of age and older who are or will be immunocompromised should receive two doses of RZV to prevent HZ and its associated complications.