A recent randomized controlled trial (RCT) from our group has demonstrated safety and immune response (both humoral and cell-mediated) of the live-attenuated herpes zoster (HZ) vaccine (Zostavax) in stable systemic lupus erythematosus (SLE) patients with a previous history of HZ or varicella infection. An important research question is whether the immunogenicity of the HZ vaccine in SLE patients is long-lasting. There is no information in the literature regarding the long-term immunogenicity and safety of Zostavax in SLE patients. This prompts the current extension study which is planned to evaluate the long-term immunogenicity and efficacy of Zostavax in our original patient cohort.

A recent RCT from our group has demonstrated safety and immune response (both humoral and cell-mediated) of the live-attenuated Zostavax in stable SLE patients with a previous history of HZ or varicella infection. An important research question is whether the immunogenicity of the HZ vaccine in SLE patients is long-lasting. There is no information in the literature regarding the long-term immunogenicity and safety of the HZ vaccine, Zostavax, in SLE patients.

Patients who had completed the original RCT and had been followed for 5 years since HZ vaccination or placebo injection were invited to participate in this extension study. Blood samples will be taken for a repeat assessment of the humoral and cell-mediated response to VZV at 5 years.

Outcomes of interest Primary outcome Difference between the two groups in the proportion of patients who have a persistent and 50% increase in IgG to VZV (humoral response to Zostavax) at 5 years compared to baseline Secondary outcomes

1. Difference between the two groups in the cell-mediated response to Zostavax at 4 years as compared to baseline
2. Vaccine efficacy - difference in the rate of clinical HZ reactivation between two groups of patients at 5 years
3. Vaccine safety - difference between the two groups in terms of SLE flares and new autoimmune phenomena at 5 years

Inclusion Criteria:

1. SLE patients who fulfill ≥4 of the 1997 ACR or the 2012 SLICC/ACR criteria for SLE or healthy controls who had participated in the original RCT
2. Age ≥18 years
3. Having completed the original RCT of HZ vaccine vs placebo
4. Having been followed for 5 years since HZ vaccination or placebo injection
5. Willing to comply with all study procedures

Exclusion Criteria:

1. Patients who refuse to participate in this long-term extension study
2. Patients in the placebo group who have subsequently received HZ vaccination
3. Patients who cannot give a written consent (mentally incapable or illiterate)

systemic lupus erythematosus (SLE) patients