INTRODUCTION: Varicella-zoster virus (VZV) infection disproportionally affects people with HIV (PWH), primarily presenting as herpes zoster. The clinical outcomes remain understudied, in terms of VZV seroprevalence in this population. In this report, the authors assessed the VZV seroprevalence, rates of VZV illness, and associated health care costs in a large cohort of PWH over 20 years.
DISCUSSION: Of 3006 PWH, VZV serology was available for 2628; of these, 2503 (95.2%) were seropositive (Zou et al.1. Only 39% of known seronegative patients were subsequently immunized for varicella. During 29,768 patients-years of follow-up, 38 hospitalizations and 138 emergency room visits due to VZV were identified. Nearly 25% of hospitalizations were due to laboratory-confirmed VZV meningitis/encephalitis. The average cost was CDN$33,001; the total measured cost of VZV illness was CDN$ 1,258,718. Given that primary VZV infection in adults carries a 25-fold higher mortality than in children, their findings show that ~3.9% of adult PWH remain at risk for chickenpox, supporting the ongoing need for VZV screening and primary immunization of PWH. They found there was only 11% of the PWH had taken the Herpes Zoster (HZ) vaccine (either live attenuated or adjuvanted subunit glycoprotein). They noted that not taking standard antiretroviral therapy (ART), having detectable HIV load, and having a lower CD4 count are major risk factors for both VZV-related hospitalization and emergency room visits. All inpatient VZV-related admissions were due to HZ, and none were due to primary varicella, with a rate of 590 health care-attended VZV cases per 100,000 patient-years over 20 years of follow-up. A similar rate in the general US population of 320 HZ cases per 100,000 patient-years has been reported (Insinga et al.2. Their results clearly document the higher risk in PWH for severe HZ-related illness. They did not capture milder disease that might still be present in the population, which would expand the risk even further. The results further emphasize the importance of optimal HIV care in controlling viral replication and normalizing CD4 counts. Earlier timing of shingles immunization in PWH seems appropriate, as 82% of HZ cases were under 50 years of age (median age was 41), while cases of HZ in the general population have a median age of 59. A publicly funded shingles vaccination program did reduce emergency room visits by 38.2% and the vaccine program in British Columbia caused a trend of rising HZ incidence to plateau.
CONCLUSION: This was the first large-scale study to describe over 2 decades of VZV seroprevalence, immunization status, the incidence of serious VZV disease in PWH and associated costs. Despite the use of modern ART, the findings in a large cohort of PWH indicate that HZ still occurs more frequently and at an earlier age in PWH than in the general population, causing both morbidity and significant costs to health-care. The majority of PWH appear to be VZV seropositive and eligible for shingles vaccination. Despite the availability of these vaccinations, they appear to be underutilized, thereby presenting a missed opportunity for improving care and minimizing health care costs. Funding of HZ vaccination appears to be challenging, but documenting the potentially avoidable costs (>CDN$ 1,200,000) in this study, may be an initial step in justifying the economic argument for funded zoster vaccines in PWH. The authors suggest that further cost-effectiveness studies of shingles vaccination are warranted to address the continued burden of VZV and its complications in PWH.
REFERENCES:
- Zou, H., H.B. Krentz, R. Lang, B. Beckthold, K. Fonseca, and M.J. Gill. (2022). Seropositivity, Risks, and Morbidity From Varicella-Zoster Virus Infections in an Adult PWH Cohort From 2000-2020. Open Forum Infect Dis. Aug 9:9(8):ofac395. Https://doi.org/10.1093/ofid/ofac395
- Insinga, R.P, R.F. Itzler, J.M. Pellissier, P. Saddier, and A.A. Nikas. (2005) The incidence of herpes zoster in a United States administrative database. J. Gen Intern Med 20;748-753.
