Comparative Immune Responses to Licensed Herpes Zoster Vaccines

The contributions of T cell-mediated immunity to protection from vaccine-preventable diseases: A primer

In the face of the ever-present burden of emerging and reemerging infectious diseases, there is a growing need to comprehensively assess individual- and population-level immunity to vaccine-preventable diseases (VPDs). Many of these efforts, however, focus exclusively on antibody-mediated immunity, ignoring the role of T cells. Aimed at clinicians, public health practioners, and others who play central roles in human vaccine research but do not have formal training in immunology, we review how vaccines against infectious diseases elicit T cell responses, what types of vaccines elicit T cell responses, and how T cell responses are measured. We then use examples to demonstrate six ways that T cells contribute to protection from VPD, including directly mediating protection, enabling antibody responses, reducing disease severity, increasing cross-reactivity, improving durability, and protecting special populations. We conclude with a discussion of challenges and solutions to more widespread consideration of T cell responses in clinical vaccinology.

Lipo-pam™ adjuvanted herpes zoster vaccine induces potent gE-specific cellular and humoral immune responses

Herpes zoster (HZ), also known as shingles, is caused by the reactivation of latent varicella-zoster virus (VZV). Decreased VZV-specific T-cell immune responses significantly contribute to the development of HZ. Shingrix is a recombinant zoster vaccine that is currently used to prevent HZ. However, Shingrix has high reactogenicity and pain at the injection site due to QS21, one of the adjuvant components. In this study, we developed a new herpes zoster vaccine formulation called CVI-VZV-001, containing gE protein and a novel liposome-based adjuvant Lipo-pam™, which consists of two TLR agonists. We evaluated the immunogenicity of CVI-VZV-001 in mouse and rabbit models. CVI-VZV-001 elicited robust gE-specific T-cell immune responses and gE-specific antibody production. Specifically, CVI-VZV-001 induced polyfunctional CD4+ T cell populations that secrete multiple cytokines. Furthermore, CVI-VZV-001 sustained the gE-specific immune responses for up to six months after immunization. To ensure CVI-VZV-001's safety for further development, we conducted a good laboratory practice (GLP) toxicity test, which confirmed that CVI-VZV-001 is safe for use. At present, CVI-VZV-001 is undergoing phase I clinical trials. This study suggests that CVI-VZV-001 can be a potent candidate for the HZ vaccine with high immunogenicity and safety.

Detection of viral RNA and DNA and immune response following administration of live attenuated measles and varicella vaccines in children with chronic liver disease

Infections preventable by live virus vaccines are surging in the setting of decreased herd immunity. Many children with chronic liver diseases (CLDs) are unimmunized and at increased risk for infection due to guidelines recommending against live vaccines within 4 weeks pretransplant. This prospective study of 21 children with CLD and 13 healthy controls defined the timing of measles virus and varicella-zoster virus (VZV) RNA- and DNA-emia following vaccination and compared immune responses to measles and varicella vaccines in both groups. Measles virus RNA and VZV DNA real-time PCR were measured weekly following vaccination; measles virus RNA was undetectable in all by 14 days postvaccination, but VZV DNA, which can be managed with antivirals, was detected in 1 child in the CLD group at 21 days and 1 control at 28 days postvaccination. Humoral or cell-mediated vaccine response was 100% to measles virus and 94% to VZV in the CLD group postvaccination, whereas it was 100% to both vaccines in controls. Our pilot study suggests that both live vaccines can be safely and effectively administered up to 14 days prior to transplantation in children with CLD. We anticipate this will improve vaccination rates and thus decrease rates of vaccine-preventable infections in vulnerable children with CLD.

CD4/CD8 Ratio: An Independent Predictor of Herpes Zoster in Patients With Autoimmune Inflammatory Rheumatic Diseases

BACKGROUND

A higher incidence of herpes zoster (HZ) was found in people with decreased cell-mediated immunity. However, the relationship between cellular immunity and HZ infection in patients with autoimmune inflammatory rheumatic diseases (AIRD) remains elusive.

OBJECTIVE

To investigate the role of CD4/CD8 ratio in patients with AIRD and HZ.

METHODS

This case-control study compared AIRD patients with and without HZ. We chose 70 AIRD patients with HZ as the experimental group and 140 AIRD patients without HZ as the control group. The clinical and laboratory findings were assessed in each trial participant.

RESULTS

The CD4/CD8 ratio (odds ratio [OR], 0.22; 95% confidence interval [CI], 0.10-0.49) was independently associated with the occurrence of HZ after adjusting for various confounders. Nonlinear analysis has unveiled a more profound nonlinear relationship between the CD4/CD8 ratio and the occurrence of HZ in patients with AIRD. The OR of HZ increased with a decreasing CD4/CD8 ratio before the turning point of 2. The adjusted regression coefficient was 0.14 (95% CI, 0.05-0.37, p<0.0001) for CD4/CD8 ratio less than 2.

CONCLUSION

The CD4/CD8 ratio was expected to be a very promising quantitative biomarker for predicting the risk of developing HZ in patients with AIRD.

Immunogenicity of Recombinant Zoster Vaccine: A Systematic Review, Meta-Analysis, and Meta-Regression

BACKGROUND

The adjuvanted recombinant zoster vaccine (RZV), consisting of varicella-zoster virus glycoprotein E (gE) and the AS01B adjuvant system, effectively prevents herpes zoster (HZ). In the absence of a well-defined correlate of protection, it is important to monitor the RZV immune response, as a proxy of clinical effectiveness.

METHODS

This systematic review examined post-vaccination parameters: humoral and cell-mediated immunity, avidity index, geometric mean concentration of antibody (GMC), and immunity persistence. The meta-analysis used a random-effects model, and subgroup and meta-regression analyses were conducted.

RESULTS

Among 37 included articles, after one month from RZV-dose 2, the pooled response rate for anti-gE humoral immunity was 95.2% (95%CI 91.9-97.2), dropping to 77.6% (95%CI 64.7-86.8) during immunosuppression. The anti-gE cell-mediated immunity-specific response reached 84.6% (95%CI 75.2-90.9). Varying factors, such as age, sex, coadministration with other vaccines, prior HZ, or live-attenuated zoster vaccine, did not significantly affect response rates. RZV induced a substantial increase in gE avidity. Immunity persistence was confirmed, with more rapid waning in the very elderly.

CONCLUSIONS

This systematic review indicates that RZV elicits robust immunogenicity and overcomes immunocompromising conditions. The findings underscore the need for further research, particularly on long-term immunity, and have the potential to support HZ vaccination policies and programs.

Adjuvant system AS01: from mode of action to effective vaccines

INTRODUCTION

The use of novel adjuvants in human vaccines continues to expand as their contribution to preventing disease in challenging populations and caused by complex pathogens is increasingly understood. AS01 is a family of liposome-based vaccine Adjuvant Systems containing two immunostimulants: 3-O-desacyl-4'-monophosphoryl lipid A and the saponin QS-21. AS01-containing vaccines have been approved and administered to millions of individuals worldwide.

AREAS COVERED

Here, we report advances in our understanding of the mode of action of AS01 that contributed to the development of efficacious vaccines preventing disease due to malaria, herpes zoster, and respiratory syncytial virus. AS01 induces early innate immune activation that induces T cell-mediated and antibody-mediated responses with optimized functional characteristics and induction of immune memory. AS01-containing vaccines appear relatively impervious to baseline immune status translating into high efficacy across populations. Currently licensed AS01-containing vaccines have shown acceptable safety profiles in clinical trials and post-marketing settings.

EXPERT OPINION

Initial expectations that adjuvantation with AS01 could support effective vaccine responses and contribute to disease control have been realized. Investigation of the utility of AS01 in vaccines to prevent other challenging diseases, such as tuberculosis, is ongoing, together with efforts to fully define its mechanisms of action in different vaccine settings.

Recombinant zoster vaccine in immunocompetent and immunocompromised adults: A review of clinical studies

Herpes zoster (HZ) is a debilitating vaccine-preventable disease. Impairment of cell-mediated immunity, as observed with aging and immunosuppressive disorders and therapies, increases risk. Recombinant zoster vaccine (RZV) is efficacious against HZ in adults aged ≥50 years in different settings, and in immunocompromised adults aged ≥18 years who are at increased risk of developing HZ. RZV is the first and only HZ vaccine approved for use in immunocompromised adults globally, including in Europe and the US. RZV has a clinically acceptable safety profile and elicits robust immune responses in adults aged ≥50 years, and in immunocompromised adults aged ≥18 years who are at increased risk of HZ. Additionally, RZV is efficacious against HZ complications such as post-herpetic neuralgia and HZ-related pain. This review updates knowledge from a randomized controlled trial setting on the efficacy, safety, immunogenicity, and impact on quality of life of RZV.

Advances in understanding the mechanism of action of adult vaccines

The occurrence of herpes zoster (HZ) correlates with declining memory T cells that had responded to earlier infection with varicella-zoster virus (VZV). There are especially lower T cell responses to the single immunodominant VZV protein glycoprotein E (gE) in people over 50 years of age, although antibody responses to VZV persist. Therefore, a live attenuated zoster vaccine (ZVL) aimed at restoring T cell responses was developed. Surprisingly, a recombinant zoster vaccine (RZV) consisting of gE combined with the AS01B adjuvant system proved superior in efficacy and durability. In this issue of the JCI, Laing, Ford, and colleagues showed that both vaccines stimulated preimmunization naive CD4+ T cells, not just memory CD4+ T cells, to gE, and recruited these naive responses into the overall memory response. However, compared with ZVL, RZV stimulated this response to a much greater degree. These results will help guide development of more effective and durable vaccines for older individuals.

Healthy ageing: Herpes zoster infection and the role of zoster vaccination

Populations are ageing worldwide, with considerable time lived in ill-health, putting upwards pressure on healthcare budgets. Healthy ageing is defined as maintaining functional ability, including the ability to: meet basic needs; learn, grow and make decisions; be mobile; build and maintain relationships; and contribute to society. The risk and impact of infectious diseases increase with age due to immunosenescence. Vaccination can help to prevent disease in older adults, promoting healthy ageing and active lives. Herpes zoster (HZ) occurs when the varicella zoster virus is reactivated due to declining immunity. HZ is common, with a lifetime risk of one-third, and increases in incidence with age. HZ is associated with severe and intense pain, substantially affecting the functional status of patients as well as their overall health-related quality of life. HZ and its complications may result in prolonged morbidity, including persistent pain (post-herpetic neuralgia, PHN), hearing impairment, vision loss and increased risk of stroke and myocardial infarction. HZ and PHN are difficult to treat, substantiating the benefits of prevention. Vaccines to prevent HZ include a recombinant zoster vaccine (RZV). RZV has shown efficacy against the HZ burden of disease and HZ burden of interference on activities of daily living of over 90% in immunocompetent adults aged ≥50 years. Vaccine efficacy against HZ was maintained at over 70% at 10 years post-vaccination. Adult vaccination, including against HZ, has the potential to reduce burden of disease, thus helping to maintain functioning and quality of life to support healthy ageing in older adults.

Vaccines for preventing herpes zoster in older adults

BACKGROUND

Herpes zoster, commonly known as shingles, is a neurocutaneous disease caused by the reactivation of the virus that causes varicella (chickenpox). After resolution of the varicella episode, the virus can remain latent in the sensitive dorsal ganglia of the spine. Years later, with declining immunity, the varicella zoster virus (VZV) can reactivate and cause herpes zoster, an extremely painful condition that can last many weeks or months and significantly compromise the quality of life of the affected person. The natural process of ageing is associated with a reduction in cellular immunity, and this predisposes older adults to herpes zoster. Vaccination with an attenuated form of the VZV activates specific T-cell production avoiding viral reactivation. Two types of herpes zoster vaccines are currently available. One of them is the single-dose live attenuated zoster vaccine (LZV), which contains the same live attenuated virus used in the chickenpox vaccine, but it has over 14-fold more plaque-forming units of the attenuated virus per dose. The other is the recombinant zoster vaccine (RZV) which does not contain the live attenuated virus, but rather a small fraction of the virus that cannot replicate but can boost immunogenicity. The recommended schedule for the RZV is two doses two months apart. This is an update of a Cochrane Review first published in 2010, and updated in 2012, 2016, and 2019.

OBJECTIVES

To evaluate the effectiveness and safety of vaccination for preventing herpes zoster in older adults.

SEARCH METHODS

For this 2022 update, we searched the Cochrane Central Register of Controlled Trials (CENTRAL 2022, Issue 10), MEDLINE (1948 to October 2022), Embase (2010 to October 2022), CINAHL (1981 to October 2022), LILACS (1982 to October 2022), and three trial registries.

SELECTION CRITERIA

We included studies involving healthy older adults (mean age 60 years or older). We included randomised controlled trials (RCTs) or quasi-RCTs comparing zoster vaccine (any dose and potency) versus any other type of intervention (e.g. varicella vaccine, antiviral medication), placebo, or no intervention (no vaccine). Outcomes were cumulative incidence of herpes zoster, adverse events (death, serious adverse events, systemic reactions, or local reaction occurring at any time after vaccination), and dropouts.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included two new studies involving 1736 participants in this update. The review now includes a total of 26 studies involving 90,259 healthy older adults with a mean age of 63.7 years. Only three studies assessed the cumulative incidence of herpes zoster in groups that received vaccines versus placebo. Most studies were conducted in high-income countries in Europe and North America and included healthy Caucasians (understood to be white participants) aged 60 years or over with no immunosuppressive comorbidities. Two studies were conducted in Japan and one study was conducted in the Republic of Korea. Sixteen studies used LZV. Ten studies tested an RZV. The overall certainty of the evidence was moderate, which indicates that the intervention probably works. Most data for the primary outcome (cumulative incidence of herpes zoster) and secondary outcomes (adverse events and dropouts) came from studies that had a low risk of bias and included a large number of participants. The cumulative incidence of herpes zoster at up to three years of follow-up was lower in participants who received the LZV (one dose subcutaneously) than in those who received placebo (risk ratio (RR) 0.49, 95% confidence interval (CI) 0.43 to 0.56; risk difference (RD) 2%; number needed to treat for an additional beneficial outcome (NNTB) 50; moderate-certainty evidence) in the largest study, which included 38,546 participants. There were no differences between the vaccinated and placebo groups for serious adverse events (RR 1.08, 95% CI 0.95 to 1.21) or deaths (RR 1.01, 95% CI 0.92 to 1.11; moderate-certainty evidence). The vaccinated group had a higher cumulative incidence of one or more adverse events (RR 1.71, 95% CI 1.38 to 2.11; RD 23%; number needed to treat for an additional harmful outcome (NNTH) 4.3) and injection site adverse events (RR 3.73, 95% CI 1.93 to 7.21; RD 28%; NNTH 3.6; moderate-certainty evidence) of mild to moderate intensity. These data came from four studies with 6980 participants aged 60 years or older. Two studies (29,311 participants for safety evaluation and 22,022 participants for efficacy evaluation) compared RZV (two doses intramuscularly, two months apart) versus placebo. Participants who received the new vaccine had a lower cumulative incidence of herpes zoster at 3.2 years follow-up (RR 0.08, 95% CI 0.03 to 0.23; RD 3%; NNTB 33; moderate-certainty evidence), probably indicating a favourable profile of the intervention. There were no differences between the vaccinated and placebo groups in cumulative incidence of serious adverse events (RR 0.97, 95% CI 0.91 to 1.03) or deaths (RR 0.94, 95% CI 0.84 to 1.04; moderate-certainty evidence). The vaccinated group had a higher cumulative incidence of adverse events, any systemic symptom (RR 2.23, 95% CI 2.12 to 2.34; RD 33%; NNTH 3.0), and any local symptom (RR 6.89, 95% CI 6.37 to 7.45; RD 67%; NNTH 1.5). Although most participants reported that their symptoms were of mild to moderate intensity, the risk of dropouts (participants not returning for the second dose, two months after the first dose) was higher in the vaccine group than in the placebo group (RR 1.25, 95% CI 1.13 to 1.39; RD 1%; NNTH 100, moderate-certainty evidence). Only one study reported funding from a non-commercial source (a university research foundation). All other included studies received funding from pharmaceutical companies. We did not conduct subgroup and sensitivity analyses AUTHORS' CONCLUSIONS: LZV (single dose) and RZV (two doses) are probably effective in preventing shingles disease for at least three years. To date, there are no data to recommend revaccination after receiving the basic schedule for each type of vaccine. Both vaccines produce systemic and injection site adverse events of mild to moderate intensity. The conclusions did not change in relation to the previous version of the systematic review.

Nonclinical safety evaluation of two vaccine candidates for herpes simplex virus type 2 to support combined administration in humans

Herpes simplex virus type 2 (HSV-2) is the most common cause of genital disease worldwide. The development of an effective HSV-2 vaccine would significantly impact global health based on the psychological distress caused by genital herpes for some individuals, the risk transmitting the infection from mother to infant, and the elevated risk of acquiring HIV-1. Five nonclinical safety studies were conducted with the replication defective HSV529 vaccine, alone or adjuvanted with GLA-SE, and the G103 subunit vaccine containing GLA-SE. A biodistribution study was conducted in guinea pigs to evaluate distribution, persistence, and shedding of HSV529. A preliminary immunogenicity study was conducted in rabbits to demonstrate HSV529-specific humoral response and its enhancement by GLA-SE. Three repeated-dose toxicity studies, one in guinea pigs and two in rabbits, were conducted to assess systemic toxicity and local tolerance of HSV529, alone or adjuvanted with GLA-SE, or G103 containing GLA-SE. Data from these studies show that both vaccines are safe and well tolerated and support the ongoing HSV-2 clinical trial in which the two vaccine candidates will be given either sequentially or concomitantly to explore their potential synergistic and incremental effects.

Development of antibody-dependent cellular cytotoxicity in response to recombinant and live-attenuated herpes zoster vaccines

Zoster vaccines generate antibody responses against varicella-zoster virus (VZV). We compared antibody-dependent cell cytotoxicity (ADCC) elicited by zoster vaccine live (ZVL) and recombinant zoster vaccine (RZV). ADCC mediated by antibodies against VZV lysate (VZV-ADCC) and recombinant glycoprotein E (gE-ADCC) was measured using plasma from 20 RZV- and 20 ZVL-recipients, including half 50-60-years-old and half ≥70-years-old. Solid phase-bound anti-VZV antibodies stimulated TNFα in NK cells as measured by flow cytometry or ELISA. VZV-ADCC pre- and post-immunization was higher in younger vaccinees. ZVL did not appreciably increase VZV-ADCC, whereas RZV increased VZV-ADCC in older vaccinees. ELISA-measured gE-ADCC was similar across groups pre-immunization; significantly increased after ZVL; and RZV and was higher in younger RZV than ZVL recipients. IgG3 antibodies increased after RZV and ZVL, with greater anti-gE than anti-VZV responses. Moreover, gE-ADCC strongly correlated with anti-gE antibody avidity, but there were no appreciable correlations between VZV-ADCC and avidity. NK cells stimulated by anti-gE antibodies showed increased IFNγ and CD107a expression, which was not observed with anti-VZV antibodies. In conclusion, anti-gE antibodies generated more robust ADCC than anti-VZV antibodies. RZV induced higher ADCC antibodies than ZVL depending on the antigen and age of vaccinees. Older adults had lower ADCC antibodies before and after vaccination than younger adults.

Adjuvanted recombinant zoster vaccine in solid organ transplant and hematopoietic stem-cell transplant recipients

PURPOSE OF REVIEW

Hematopoietic stem-cell (HSCT) and solid organ transplant (SOT) recipients are particularly at risk to develop herpes zoster and its complications. A recently approved nonlive, adjuvanted recombinant zoster vaccine (aRZV) is a potential candidate to provide durable prevention of herpes zoster. This review summarizes current scientific evidence and expert recommendations for its use in these populations and offers practical clinical guidance.

RECENT FINDINGS

Recent clinical trials have shown aRZV to be well tolerated and efficacious in the prevention of herpes zoster, even in the elderly. Data are emerging that this vaccine might also be effective in immunocompromised individuals, such as SOT and HSCT recipients. Evidence is sparse regarding optimal timing of vaccination and durability of responses. However, several specialized societies have already established expert-based aRZV immunization recommendations for these vulnerable populations.

SUMMARY

Practical considerations, safety concerns, and timing of vaccine administration vary from one immunocompromised subpopulation to another. Initial studies show that aRZV has a favorable safety and immunogenicity profile in SOT and HSCT recipients. However, data are sparse, particularly in allogeneic HSCT, and practical recommendations are mostly based on expert opinion. Additional research is needed to offer better insight on aRZV administration in immunocompromised patients.

Development of a perfusion process for serum-free adenovirus vector herpes zoster vaccine production

Herpes zoster is caused by reactivation of the varicella zoster virus (VZV). Researching and developing a herpes zoster vaccine will help to decrease the incidence of herpes zoster. To increase the bioreactor productivity, a serum-free HEK293 cell perfusion process with adenovirus vector herpes zoster (rAd-HZ) vaccine production was developed efficiently using the design of experiment (DoE) method. First, serum-free media for HEK293 cells were screened in both batch and semi-perfusion culture modes. Then, three optimal media were employed in a medium mixture design to improve cell culture performance, and the 1:1 mixture of HEK293 medium and MCD293 medium (named HM293 medium) was identified as the optimal formulation. On the basis of the HM293 medium, the relationship of critical process parameters (CPPs), including the time of infection (TOI), multiplicity of infection (MOI), pH, and critical quality attributes (CQAs) (adenovirus titer (Titer), cell-specific virus yield (CSVY), adenovirus fold expansion (Fold)) of rAd-HZ production was investigated using the DoE approach. Furthermore, the robust setpoint and design space of these CPPs were explored. Finally, the rAd-HZ production process with parameters at a robust setpoint (TOI = 7.2 × 10⁶ cells/mL, MOI = 3.7, and pH = 7.17) was successfully scaled-up to a 3-L bioreactor with an alternating tangential flow system, yielding an adenovirus titer of 3.0 × 10¹⁰ IFU/mL, a CSVY of 4167 IFU/cells, a Fold of 1117 at 2 days post infection (dpi). The DoE approach accelerated the development of a HEK293 serum-free medium and of a robust adenovirus production process.

An adjuvanted zoster vaccine elicits potent cellular immune responses in mice without QS21

Herpes zoster (HZ) is caused by reactivation of latent varicella-zoster virus (VZV) when VZV-specific cellular immunity is insufficient to control reactivation. Currently, Shingrix, which contains the VZV gE protein and GSK’s AS01_B adjuvant composed of liposomes formulated with cholesterol, monophosphoryl lipid A (MPL) and QS21, is used for prevention of HZ. However, reactogenicity to Shingrix is common leading to poor patient compliance in receiving one or both shots. Here, we evaluated the immunogenicity of a newly formulated gE protein-based HZ vaccine containing Second-generation Lipid Adjuvant (SLA), a synthetic TLR4 ligand, formulated in an oil-in-water emulsion (SLA-SE) without QS21 (gE/SLA-SE). In VZV-primed mouse models, gE/SLA-SE-induced gE-specific humoral and cellular immune responses at comparable levels to those elicited by Shingrix in young mice, as both gE/SLA-SE and Shingrix induce polyfunctional CD4⁺ T-cell responses. In aged mice, gE/SLA-SE elicited more robust gE-specific T-cell responses than Shingrix. Furthermore, gE/SLA-SE-induced T-cell responses were sustained until 5 months after immunization. Thus, QS21-free, gE/SLA-SE is a promising candidate for development of gE-based HZ vaccines with high immunogenicity—particularly when targeting an older population.

Fraternal Twins: The Enigmatic Role of the Immune System in Alphaherpesvirus Pathogenesis and Latency and Its Impacts on Vaccine Efficacy

Although the establishment, maintenance and reactivation from alphaherpesvirus latency is far from fully understood, some things are now manifestly clear: Alphaherpesvirus latency occurs in neurons of the peripheral nervous system and control of the process is multifactorial and complex. This includes components of the immune system, contributions from non-neuronal cells surrounding neurons in ganglia, specialized nucleic acids and modifications to the viral DNA to name some of the most important. Efficacious vaccines have been developed to control both acute varicella and zoster, the outcome of reactivation, but despite considerable effort vaccines for acute herpes simplex virus (HSV) infection or reactivated lesions have thus far failed to materialize despite considerable effort. Given the relevance of the immune system to establish and maintain HSV latency, a vaccine designed to tailor the HSV response to maximize the activity of components most critical for controlling reactivated infection might limit the severity of recurrences and hence reduce viral transmission. In this review, we discuss the current understanding of immunological factors that contribute to HSV and VZV latency, identify differences between varicella-zoster virus (VZV) and HSV that could explain why vaccines have been valuable at controlling VZV disease but not HSV, and finish by outlining possible strategies for developing effective HSV vaccines.

Precision Vaccine Adjuvants for Older Adults: A Scoping Review

Older adults, defined as those ≥60 years of age, are a growing population vulnerable to infections including severe acute respiratory syndrome coronavirus 2. Although immunization is a key to protecting this population, immunosenescence can impair responses to vaccines. Adjuvants can increase the immunogenicity of vaccine antigens but have not been systematically compared in older adults. We conducted a scoping review to assess the comparative effectiveness of adjuvants in aged populations. Adjuvants AS01, MF59, AS03, and CpG-oligodeoxynucleotide, included in licensed vaccines, are effective in older human adults. A growing menu of investigational adjuvants, such as Matrix-M and CpG plus alum, showed promising results in early phase clinical trials and preclinical studies. Most studies assessed only 1 or 2 adjuvants and no study has directly compared >3 adjuvants among older adults. Enhanced preclinical approaches enabling direct comparison of multiple adjuvants including human in vitro modeling and age-specific animal models may derisk and accelerate vaccine development for older adults.

Knowledge and Attitudes Concerning Herpes Zoster among People with COPD: An Interventional Survey Study

Herpes zoster (HZ) is common in older adults with conditions such as chronic obstructive pulmonary disease (COPD). Effective prevention is available through vaccination, but HZ vaccine uptake remains incomplete. Using an online survey of people with self-reported COPD, ShiPPS assessed HZ risk awareness, HZ vaccine use and barriers, and the impact of an HZ educational video on vaccine intent. USA members of the COPD Foundation’s Patient-Powered Research Network aged >50 years were surveyed in fall 2020. The responses were analyzed using descriptive and comparative statistics. Of the 735 respondents (59.6% female, mean age 68.5 years), 192 (26.1%) reported previous HZ, of whom 49 (25.5%) reported increased COPD symptoms during HZ episodes. Most participants (94.0%) knew of HZ vaccines, but only 33.1% reported receiving the Advisory Committee on Immunization Practices-preferred recombinant HZ vaccination. The recall of receiving HZ vaccine recommendations differed by the site attended: 68.8% primary care, 26.6% pulmonology offices. Most (74.7%) were unaware that COPD increases HZ risk. Among unvaccinated participants, interest in getting the HZ vaccine increased from 32.0% to 73.5% after watching the video. These results highlight the need for people with COPD to receive further HZ education, such as the five-minute video, and HZ vaccine recommendations from healthcare professionals.

Herpes Zoster Ophthalmicus: A Devastating Disease Coming Back with Vengeance or Finding Its Nemesis?

Herpes zoster ophthalmicus is a frequent, painful, and debilitating condition caused by the reactivation of the varicella-zoster virus alongside the ophthalmic branch of the trigeminal nerve. Twenty-five percent of adults will develop the disease during their lifetime with the risk increasing to one in two over the age of 50. Herpes zoster ophthalmicus presents with a plethora of ocular manifestations ranging from the characteristic rash in the distribution of the ophthalmic branch of the fifth cranial nerve to more severe keratouveitis, disciform keratitis, and even retinal necrosis. Up to 20% of affected patients develop post-herpetic neuralgia which can persist for years after the acute episode, resulting in potentially devastating consequences for the patient's social, financial, and professional circumstances, as well as their quality of life and daily activities. Shingles prevention studies indicated that the herpes zoster vaccine markedly reduces the burden of the disease, as well as the incidence of both infection and post-herpetic neuralgia. Here we review the vaccinations available for herpes zoster, the reasons behind their limited adoption so far, as well as the future perspectives and challenges associated with this debilitating disease in the era of herpes zoster vaccination and coronavirus disease pandemic.

The Adjuvanted Recombinant Zoster Vaccine in Adults Aged ≥65 Years Previously Vaccinated With a Live-Attenuated Herpes Zoster Vaccine

BACKGROUND

Efficacy of the live-attenuated herpes zoster (HZ) vaccine (ZVL) wanes substantially over time. We evaluated immunogenicity and safety of the adjuvanted recombinant zoster vaccine (RZV) in previous ZVL recipients.

METHODS

Adults aged ≥65 years who were previously vaccinated with ZVL ≥5 years earlier (n = 215) were group-matched with ZVL-naive individuals (n = 215) and vaccinated with RZV. Glycoprotein E (gE)-specific humoral and cell-mediated immune responses and the correlation between them, polyfunctional gE-specific CD4 T-cell responses, safety, and confirmed HZ cases were assessed.

RESULTS

Through 12 months after dose 2, anti-gE antibody concentrations, gE-specific CD4 T-cell frequencies, and activation marker profiles were similar between groups. Safety outcomes were also similar. No HZ episodes were confirmed.

CONCLUSIONS

RZV induced strong humoral and polyfunctional cell-mediated immune responses that persisted above prevaccination levels through 1 year after dose 2 in adults aged ≥65 years irrespective of previous ZVL vaccination. The RZV safety profile was not affected.

CLINICAL TRIALS REGISTRATION

NCT02581410.

Risk Factors for Herpes Zoster in Patients with Chronic Kidney Disease: A Case-Control Study

(1) Background: Chronic kidney disease (CKD) increases the susceptibility to the presence of herpes zoster (HZ). Little is known about the risk factors of HZ in CKD patients; (2) Methods: This is a case-control study. CKD patients diagnosed with HZ between January 2015 and June 2021 in a tertiary hospital were identified. One age- and gender- matched control was paired for each case, matched to the date of initial HZ diagnosis. Conditional multiple logistic regression was used to evaluate the risk factors associated with the presence of HZ; (3) Results: Forty-seven HZ patients and controls were identified. In general, about 73.40% (69 out of 94) patients were classified at IV to V stages of CKD. Immunosuppressive agents (p = 0.0012) and dialysis therapy (p = 0.021) were reported more frequently in the HZ cohort. Compared with the control group, the total white cell count and lymphocyte count were significantly lower in the HZ group (p value of 0.032 and 0.003, respectively). The conditional logistics regression model revealed that previous immunosuppressants administration (odds ratio: 10.861, 95% CI: 2.092~56.392, p = 0.005) and dialysis therapy (odds ratio: 3.293, 95% CI: 1.047~10.355, p = 0.041) were independent risk factors of HZ in the CKD population; (4) Conclusions: Dialysis and immunosuppressants therapy were associated with greater risk of HZ disease in CKD patients. Further guideline may highlight the necessity of zoster vaccine for patients with CKD, who undertake associated treatment.

Vaccines for older adults

The proportion of the global population aged 65 and older is rapidly increasing. Infections in this age group, most recently with SARS-CoV-2, cause substantial morbidity and mortality. Major improvements have been made in vaccines for older people, either through the addition of novel adjuvants-as in the new recombinant zoster vaccine and an adjuvanted influenza vaccine-or by increasing antigen concentration, as in influenza vaccines. In this article we review improvements in immunization for the three most important vaccine preventable diseases of aging. The recombinant zoster vaccine has an efficacy of 90% that is minimally affected by the age of the person being vaccinated and persists for more than four years. Increasing antigen dose or inclusion of adjuvant has improved the immunogenicity of influenza vaccines in older adults, although the relative effectiveness of the enhanced influenza vaccines and the durability of the immune response are the focus of ongoing clinical trials. Conjugate and polysaccharide pneumococcal vaccines have similar efficacy against invasive pneumococcal disease and pneumococcal pneumonia caused by vaccine serotypes in older adults. Their relative value varies by setting, depending on the prevalence of vaccine serotypes, largely related to conjugate vaccine coverage in children. Improved efficacy will increase public confidence and uptake of these vaccines. Co-administration of these vaccines is feasible and important for maximal uptake in older people. Development of new vaccine platforms has accelerated following the arrival of SARS-CoV-2, and will likely result in new vaccines against other pathogens in the future.

Understanding immunosenescence and its impact on vaccination of older adults

Older adults are more susceptible to viral and bacterial infection, and experience higher incidence and severity of infectious diseases. Although vaccination is the most logical solution in preventing infectious diseases, primary vaccine responses in individuals aged ≥65 years-old fail to generate complete protection. This is presumably attributed to immunosenescence, a term that describes functional differences associated with the immune system and natural age advancement. Both the innate and adaptive immune systems experience age-related impairments that contribute to insufficient protection following vaccination. This review addresses current knowledge of age-related changes that affect vaccine responsiveness; including the deficits in innate cell functions, dampened humoral and cell-mediated immune responses, current vaccination schedules for older adults, and concludes with potential strategies for improving vaccine efficacy specifically for this age group. Due to an age-related decline in immunity and poor vaccine responses, infectious diseases remain a burden among the aged population.

Alphaherpesvirus Vaccines

Prophylactic and therapeutic vaccines for the alphaherpesviruses including varicella zoster virus (VZV) and herpes simplex virus types 1 and 2 have been the focus of enormous preclinical and clinical research. A live viral vaccine for prevention of chickenpox and a subunit therapeutic vaccine to prevent zoster are highly successful. In contrast, progress towards the development of effective prophylactic or therapeutic vaccines against HSV-1 and HSV-2 has met with limited success. This review provides an overview of the successes and failures, the different types of immune responses elicited by various vaccine modalities, and the need to reconsider the preclinical models and immune correlates of protection against HSV.

Immune Responses to Varicella-Zoster Virus Glycoprotein E Formulated with Poly(Lactic-co-Glycolic Acid) Nanoparticles and Nucleic Acid Adjuvants in Mice

The subunit herpes zoster vaccine Shingrix is superior to attenuated vaccine Zostavax in both safety and efficacy, yet its unlyophilizable liposome delivery system and the limited supply of naturally sourced immunological adjuvant QS-21 still need to be improved. Based on poly(lactic-co-glycolic acid) (PLGA) delivery systems that are stable during the lyophilization and rehydration process and using a double-emulsion (w/o/w) solvent evaporation method, we designed a series of nanoparticles with varicella-zoster virus antigen glycoprotein E (VZV-gE) as an antigen and nucleic acids including polyinosinic-polycytidylic acid (Poly I:C) and phosphodiester CpG oligodeoxynucleotide (CpG ODN), encapsulated as immune stimulators. While cationic lipids (DOTAP) have more potential than neutral lipids (DOPC) for activating gE-specific cell-mediated immunity (CMI) in immunized mice, especially when gE is encapsulated in and presented on the surface of nanoparticles, PLGA particles without lipids have the greatest potential to induce not only the highest gE-specific IgG titers but also the strongest gE-specific CMI responses, including the highest proportions of interferon-γ (IFN-γ)- and interleukin-2 (IL-2)-producing CD4+/CD8+ T cells according to a flow cytometry assay and the greatest numbers of IFN-γ- and IL-2-producing splenocytes according to an enzyme-linked immunospot (ELISPOT) assay. These results showed that immune-stimulating nucleic acids together with the PLGA delivery system showed promise as a safe and economical varicella and zoster vaccine candidate.

Zoster Vaccination in Older Adults: Efficacy and Public Health Implications

Shingles and its most common disabling complication, post-herpetic neuralgia, represent a serious public health challenge in the older population. The decline in the T-cell-mediated immune response to varicella zoster virus after age 50 is clearly associated with increased risk of viral reactivation, causing an acutely painful zoster rash, which may have a severe prodrome of dermatomal pain and persist as seriously debilitating post-herpetic neuralgia well beyond the resolution of the rash. However, new vaccines and adjuvants are being developed and trialed and are now more effective in preventing shingles and the sequelae of post-herpetic neuralgia. Those vaccines that possess the ability to enhance antigen presentation and reverse memory T-cell exhaustion, as well as diminish the immune suppressive effects of regulatory T cells, are most likely to be effective in older adults.

What's New in Vaccine Science

Today vaccines can provide immunity against and treatment of a growing number of diseases including noninfectious conditions. Vaccine science continues to evolve newer and safer ways to deliver prevention and treatment of infectious and noninfectious diseases. This includes new adjuvants to enhance immunogenicity; delivery systems to reduce pain and improve acceptability; a wider range of uses including preventing emerging infectious diseases, such as Zika virus and Ebola, treatment of chronic diseases, such as cancer, and autoimmune disorders; and repurposing of existing vaccines, such as bacillus Calmette-Guérin for novel therapies.

Vaccines for Herpes Simplex: Recent Progress Driven by Viral and Adjuvant Immunology

Herpes simplex viruses (HSV) types 1 and 2 are ubiquitous. They both cause genital herpes, occasionally severe disease in the immunocompromised, and facilitate much HIV acquisition globally. Despite more than 60 years of research, there is no licensed prophylactic HSV vaccine and some doubt as to whether this can be achieved. Nevertheless, a previous HSV vaccine candidate did have partial success in preventing genital herpes and HSV acquisition and another immunotherapeutic candidate reduced viral shedding and recurrent lesions, inspiring further research. However, the entry pathway of HSV into the anogenital mucosa and the subsequent cascade of immune responses need further elucidation so that these responses could be mimicked or improved by a vaccine, to prevent viral entry and colonization of the neuronal ganglia. For an effective novel vaccine against genital herpes the choice of antigen and adjuvant may be critical. The incorporation of adjuvants of the vaccine candidates in the past, may account for their partial efficacy. It is likely that they can be improved by understanding the mechanisms of immune responses elicited by different adjuvants and comparing these to natural immune responses. Here we review the history of vaccines for HSV, those in development and compare them to successful vaccines for chicken pox or herpes zoster. We also review what is known of the natural immune control of herpes lesions, via interacting innate immunity and CD4 and CD8 T cells and the lessons they provide for development of new, more effective vaccines.

Vaccines for preventing herpes zoster in older adults

BACKGROUND

Herpes zoster, commonly known as shingles, is a neurocutaneous disease caused by the reactivation of the virus that causes varicella (chickenpox). After resolution of the varicella episode, the virus can remain latent in the sensitive dorsal ganglia of the spine. Years later, with declining immunity, the varicella zoster virus (VZV) can reactivate and cause herpes zoster, an extremely painful condition that can last many weeks or months and significantly compromise the quality of life of the affected person. The natural process of aging is associated with a reduction in cellular immunity, and this predisposes older people to herpes zoster. Vaccination with an attenuated form of the VZV activates specific T-cell production avoiding viral reactivation. The USA Food and Drug Administration has approved a herpes zoster vaccine with an attenuated active virus, live zoster vaccine (LZV), for clinical use amongst older adults, which has been tested in large populations. A new adjuvanted recombinant VZV subunit zoster vaccine, recombinant zoster vaccine (RZV), has also been approved. It consists of recombinant VZV glycoprotein E and a liposome-based AS01B adjuvant system. This is an update of a Cochrane Review last updated in 2016.

OBJECTIVES

To evaluate the effectiveness and safety of vaccination for preventing herpes zoster in older adults.

SEARCH METHODS

For this 2019 update, we searched the Cochrane Central Register of Controlled Trials (CENTRAL, Issue 1, January 2019), MEDLINE (1948 to January 2019), Embase (2010 to January 2019), CINAHL (1981 to January 2019), LILACS (1982 to January 2019), WHO ICTRP (on 31 January 2019) and ClinicalTrials.gov (on 31 January 2019).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs comparing zoster vaccine (any dose and potency) versus any other type of intervention (e.g. varicella vaccine, antiviral medication), placebo, or no intervention (no vaccine). Outcomes were incidence of herpes zoster, adverse events (death, serious adverse events, systemic reactions, or local reaction occurring at any time after vaccination), and dropouts.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 11 new studies involving 18,615 participants in this update. The review now includes a total of 24 studies involving 88,531 participants. Only three studies assessed the incidence of herpes zoster in groups that received vaccines versus placebo. Most studies were conducted in high-income countries in Europe and North America and included healthy Caucasians (understood to be white participants) aged 60 years or over with no immunosuppressive comorbidities. Two studies were conducted in Japan. Fifteen studies used LZV. Nine studies tested an RZV. The overall quality of the evidence was moderate. Most data for the primary outcome (incidence of herpes zoster) and secondary outcomes (adverse events and dropouts) came from studies that had a low risk of bias and included a large number of participants. The incidence of herpes zoster at up to three years follow-up was lower in participants who received the LZV (one dose subcutaneously) than in those who received placebo (risk ratio (RR) 0.49, 95% confidence interval (CI) 0.43 to 0.56; risk difference (RD) 2%; number needed to treat for an additional beneficial outcome (NNTB) 50; moderate-quality evidence) in the largest study, which included 38,546 participants. There were no differences between the vaccinated and placebo groups for serious adverse events (RR 1.08, 95% CI 0.95 to 1.21) or deaths (RR 1.01, 95% CI 0.92 to 1.11; moderate-quality evidence). The vaccinated group had a higher incidence of one or more adverse events (RR 1.71, 95% CI 1.38 to 2.11; RD 23%; number needed to treat for an additional harmful outcome (NNTH) 4.3) and injection site adverse events (RR 3.73, 95% CI 1.93 to 7.21; RD 28%; NNTH 3.6) of mild to moderate intensity (moderate-quality evidence). These data came from four studies with 6980 participants aged 60 years or over. Two studies (29,311 participants for safety evaluation and 22,022 participants for efficacy evaluation) compared RZV (two doses intramuscularly, two months apart) versus placebo. Participants who received the new vaccine had a lower incidence of herpes zoster at 3.2 years follow-up (RR 0.08, 95% CI 0.03 to 0.23; RD 3%; NNTB 33; moderate-quality evidence). There were no differences between the vaccinated and placebo groups in incidence of serious adverse events (RR 0.97, 95% CI 0.91 to 1.03) or deaths (RR 0.94, 95% CI 0.84 to 1.04; moderate-quality evidence). The vaccinated group had a higher incidence of adverse events, any systemic symptom (RR 2.23, 95% CI 2.12 to 2.34; RD 33%; NNTH 3.0), and any local symptom (RR 6.89, 95% CI 6.37 to 7.45; RD 67%; NNTH 1.5). Although most participants reported that there symptoms were of mild to moderate intensity, the risk of dropouts (participants not returning for the second dose, two months after the first dose) was higher in the vaccine group than in the placebo group (RR 1.25, 95% CI 1.13 to 1.39; RD 1%; NNTH 100, moderate-quality evidence). Only one study reported funding from a non-commercial source (a university research foundation). All of the other included studies received funding from pharmaceutical companies. We did not conduct subgroup and sensitivity analyses AUTHORS' CONCLUSIONS: LZV and RZV are effective in preventing herpes zoster disease for up to three years (the main studies did not follow participants for more than three years). To date, there are no data to recommend revaccination after receiving the basic schedule for each type of vaccine. Both vaccines produce systemic and injection site adverse events of mild to moderate intensity.

Mechanisms of Immune Control of Mucosal HSV Infection: A Guide to Rational Vaccine Design

Herpes Simplex Virus (HSV) is a highly prevalent sexually transmitted infection that aside from causing cold sores and genital lesions, causes complications in the immunocompromised and has facilitated a large proportion of HIV acquisition globally. Despite decades of research, there is no prophylactic HSV vaccine ready for use in humans, leaving many questioning whether a prophylactic vaccine is an achievable goal. A previous HSV vaccine trial did have partial success in decreasing acquisition of HSV2–promising evidence that vaccines can prevent acquisition. However, there is still an incomplete understanding of the immune response pathways elicited by HSV after initial mucosal infection and how best to replicate these responses with a vaccine, such that acquisition and colonization of the dorsal root ganglia could be prevented. Another factor to consider in the rational design of an HSV vaccine is adjuvant choice. Understanding the immune responses elicited by different adjuvants and whether lasting humoral and cell-mediated responses are induced is important, especially when studies of past trial vaccines found that a sufficiently protective cell-mediated response was lacking. In this review, we discuss what is known of the immune control involved in initial herpes lesions and reactivation, including the importance of CD4 and CD8 T cells, and the interplay between innate and adaptive immunity in response to primary infection, specifically focusing on the viral relay involved. Additionally, a summary of previous and current vaccine trials, including the components used, immune responses elicited and the feasibility of prophylactic vaccines looking forward, will also be discussed.

Recombinant Glycoprotein E of Varicella Zoster Virus Contains Glycan-Peptide Motifs That Modulate B Cell Epitopes into Discrete Immunological Signatures

A recombinant subunit vaccine (Shingrix^®) was recently licensed for use against herpes zoster. This vaccine is based on glycoprotein E (gE) of varicella zoster virus (VZV), the most abundantly expressed protein of VZV, harboring sites for N- and O-linked glycosylation. The subunit vaccine elicits stronger virus-specific CD4+ T cell response as well as antibody B cell response to gE, compared to the currently used live attenuated vaccine (Zostavax^®). This situation is at variance with the current notion since a live vaccine, causing an active virus infection, should be far more efficient than a subunit vaccine based on only one single viral glycoprotein. We previously found gE to be heavily glycosylated, not least by numerous clustered O-linked glycans, when it was produced in human fibroblasts. However, in contrast to Zostavax^®, which is produced in fibroblasts, the recombinant gE of Shingrix^® is expressed in Chinese hamster ovary (CHO) cells. Hence, the glycan occupancy and glycan structures of gE may differ considerably between the two vaccine types. Here, we aimed at (i) defining the glycan structures and positions of recombinant gE and (ii) identifying possible features of the recombinant gE O-glycosylation pattern contributing to the vaccine efficacy of Shingrix^®. Firstly, recombinant gE produced in CHO cells (“Shingrix situation”) is more scarcely decorated by O-linked glycans than gE from human fibroblasts (“Zostavax situation”), with respect to glycan site occupancy. Secondly, screening of immunodominant B cell epitopes of gE, using a synthetic peptide library against serum samples from VZV-seropositive individuals, revealed that the O-linked glycan signature promoted binding of IgG antibodies via a decreased number of interfering O-linked glycans, but also via specific O-linked glycans enhancing antibody binding. These findings may, in part, explain the higher protective efficacy of Shingrix^®, and can also be of relevance for development of subunit vaccines to other enveloped viruses.

Varicella Virus-Host Interactions During Latency and Reactivation: Lessons From Simian Varicella Virus

Varicella zoster virus (VZV) is a neurotropic alphaherpesvirus and the causative agent of varicella (chickenpox) in humans. Following primary infection, VZV establishes latency in the sensory ganglia and can reactivate to cause herpes zoster, more commonly known as shingles, which causes significant morbidity, and on rare occasions mortality, in the elderly. Because VZV infection is highly restricted to humans, the development of a reliable animal model has been challenging, and our understanding of VZV pathogenesis remains incomplete. As an alternative, infection of rhesus macaques with the homologous simian varicella virus (SVV) recapitulates the hallmarks of VZV infection and thus constitutes a robust animal model to provide critical insights into VZV pathogenesis and the host antiviral response. In this model, SVV infection results in the development of varicella during primary infection, generation of an adaptive immune response, establishment of latency in the sensory ganglia, and viral reactivation upon immune suppression. In this review, we discuss our current knowledge about host and viral factors involved in the establishment of SVV latency and reactivation as well as the important role played by T cells in SVV pathogenesis and antiviral immunity.