Older adults are at increased risk of severe chikungunya. Some countries advise against vaccinating ≥ 60 or ≥ 65-year-olds with the licenced live-attenuated vaccine (CHIKV LA, IXCHIQ), following severe adverse event (SAE) reports. A virus-like particle vaccine (CHIKV VLP, VIMKUNYA) is licensed in the United States (US), EU/EEA and the United Kingdom. Up to 31 August 2025, over 12,500 doses were administered in US and Germany; no SAEs in ≥ 65-year-olds were reported. Early post-authorisation data support its favourable safety profile in ≥ 65-year-olds.

Introduction Traditional live-attenuated or inactivated vaccines have limitations, including risks associated with uncontrolled replication, reduced immunogenicity, or production complexities. To address these issues, alternative platforms such as virus-like particles (VLPs) have been developed.Areas covered VLPs are self-assembling structures composed of viral proteins that mimic native viruses but are noninfectious. This review provides an overview of their structure, design and manufacture that make them an attractive platform for vaccine development. We then discuss the clinical development of some recently approved VLP vaccines and those widely used in immunization programs, summarizing the clinical trial data that underpins their efficacy and safety profiles. Additionally, we explore VLP vaccines in late-stage clinical development for respiratory syncytial virus and human metapneumovirus.Expert opinion VLPs are a versatile and promising platform for vaccine development. Their ability to mimic native viruses while eliminating the risks associated with live vaccines positions them as an attractive platform for vaccine design. Currently approved VLP vaccines demonstrate that they can provide effective protection against a wide range of diseases. Advances in VLP design and production are likely to lead to highly effective vaccines, significantly contributing to global immunization efforts.

Background: Mpox is a disease endemic to Central and West Africa. It caused outbreaks in non-endemic countries, mainly in 2022. The endemic Democratic Republic of Congo is currently experiencing its largest outbreak yet. The vaccine Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN) is approved for active immunization against mpox and smallpox. Since the outbreak in 2022, real-world studies have assessed MVA-BN's vaccine effectiveness (VE) against mpox, and this systematic literature review aims to summarize the most current evidence.Methods: Medline (via PubMed), Embase, and LILACS were searched, as well as grey literature sources and publications' bibliographies to identify observational studies published between 1/Jan/2022 and 28/Feb/2024 that estimate the VE of MVA-BN against mpox or provide risk measures that allow calculation of these VE estimates. Data were presented descriptively in tables and text; the methodological quality of included records was assessed using NHLBI/NIH quality assessment tools.Results: The literature search identified 16 records that fit the inclusion criteria. The studies took place in high-income countries and were heterogeneous in design, setting, and definition of at-risk populations. MVA-BN VE estimates against mpox infection were assessed. Where the study population was exclusively or primarily those receiving pre-exposure prophylactic vaccination, the adjusted VE estimates ranged from 35 % to 86 % (n = 8 studies) for one dose and from 66 % to 90 % (n = 5) for two doses. Where only post-exposure prophylactic vaccination was assessed, adjusted VE estimates were reported for one dose only at 78 % and 89 % (n = 2). Additionally, MVA-BN reduced the risk of mpox-related hospitalization in one study and the severity of mpox clinical manifestations in two studies.Conclusions: Despite heterogeneity in study design, setting, and at-risk populations, the reported VE estimates against mpox infection demonstrated the effectiveness of one or two doses of MVA-BN in the context of an outbreak across multiple countries.

BACKGROUND:Although cases of rabies in international travellers are uncommon, they are a fatal risk which can be alleviated through vaccination prior to travel. As international travel recovers post-COVID, it is vital that travellers are made aware of the risk of rabies when travelling to endemic countries and supported to receive the vaccine when eligible. METHODS:Online surveys were conducted in the US, Germany, Sweden and Switzerland between November 2022-January 2023 with both patients and healthcare providers (HCPs). Eligibility criteria for patients included those eligible for rabies pre-exposure prophylaxis (PrEP) due to travel location and activity; HCPs had to be providers of travel vaccinations. In both surveys, questions were asked about discussion of rabies vaccination, decision of whether to administer a rabies vaccine, recommendation to get the rabies vaccine, and final decision to get a vaccine. RESULTS:The final patient sample included n = 1557 patients who were eligible for rabies pre-exposure prophylaxis (US n = 504, Germany n = 353, Sweden n = 350, Switzerland n = 350) and n = 219 HCPs (US n = 75, Germany n = 75, Sweden n = 32, Switzerland n = 37). Although all patients in the sample were eligible for rabies vaccination, only 15 % felt they were at risk of getting rabies, and only 18 % received the rabies vaccine before their trip. HCPs reported discussing PrEP and/or PrEP and PEP with 30 % of patients presenting for travel vaccination advice, on average. CONCLUSIONS:Awareness and perception of rabies risk, and lack of consistent HCP discussion of the need for rabies PrEP may be major barriers to uptake of the vaccine for patients who are eligible to receive it.

Prevention of mpox has become an important public health interest. We aimed to evaluate the safety and immunogenicity of the Modified Vaccinia Ankara (MVA) vaccine. We conducted a systematic review and meta-analysis of randomized-controlled trials (RCTs) comparing MVA versus no intervention, placebo, or another vaccine. Outcomes included safety and immunogenicity outcomes. We also performed a systematic review of RCTs evaluating various MVA regimens. Fifteen publications were included in the quantitative meta-analysis. All but one (ACAM2000) compared MVA with placebo. We found that cardiovascular adverse events following two MVA doses were significantly more common compared to placebo (relative risk [RR] 4.07, 95% confidence interval [CI] 1.10–15.10), though serious adverse events (SAEs) were not significantly different. Following a single MVA dose, no difference was demonstrated in any adverse event outcomes. Seroconversion rates were significantly higher compared with placebo after a single or two doses. None of the RCTs evaluated clinical effectiveness in preventing mpox. This meta-analysis provides reassuring results concerning the immunogenicity and safety of MVA. Further studies are needed to confirm the immunogenicity of a single dose and its clinical effectiveness. A single vaccine dose may be considered according to vaccine availability, with preference for two doses.

Monkeypox, a zoonotic disease caused by an orthopoxvirus, results in a smallpox-like disease in humans. Since monkeypox in humans was initially diagnosed in 1970 in the Democratic Republic of the Congo (DRC), it has spread to other regions of Africa (primarily West and Central), and cases outside Africa have emerged in recent years. We conducted a systematic review of peer-reviewed and grey literature on how monkeypox epidemiology has evolved, with particular emphasis on the number of confirmed, probable, and/or possible cases, age at presentation, mortality, and geographical spread. The review is registered with PROSPERO (CRD42020208269). We identified 48 peer-reviewed articles and 18 grey literature sources for data extraction. The number of human monkeypox cases has been on the rise since the 1970s, with the most dramatic increases occurring in the DRC. The median age at presentation has increased from 4 (1970s) to 21 years (2010-2019). There was an overall case fatality rate of 8.7%, with a significant difference between clades-Central African 10.6% (95% CI: 8.4%- 13.3%) vs. West African 3.6% (95% CI: 1.7%- 6.8%). Since 2003, import- and travel-related spread outside of Africa has occasionally resulted in outbreaks. Interactions/activities with infected animals or individuals are risk behaviors associated with acquiring monkeypox. Our review shows an escalation of monkeypox cases, especially in the highly endemic DRC, a spread to other countries, and a growing median age from young children to young adults. These findings may be related to the cessation of smallpox vaccination, which provided some cross-protection against monkeypox, leading to increased human-to-human transmission. The appearance of outbreaks beyond Africa highlights the global relevance of the disease. Increased surveillance and detection of monkeypox cases are essential tools for understanding the continuously changing epidemiology of this resurging disease.

Abstract Background The ongoing monkeypox outbreak, a WHO-declared PHEIC, requires fast and broad rollout of MVA-BN vaccinations among risk groups. An initial single-dose strategy, followed by a delayed second dose beyond the approved 4-week interval, could help managing tight vaccine resources. Methods Bavarian Nordic has run a study in vaccinia-naïve participants, randomized to receive either 1 MVA-BN vaccination (N = 181) or 2 MVA-BN vaccinations 4 weeks apart (N = 183). Of note, this study also evaluated participants with prior smallpox vaccination, who received 1 MVA-BN boost (N = 200). Subsets of approximately 75 participants of the vaccinia-naïve subjects having received either 1 or 2 doses of the vaccine were administered an MVA-BN boost 2 years later. Neutralizing antibodies (nAb) were measured using Vaccinia PRNT. Results The 1xMVA-BN and 2xMVA-BN groups responded as expected to the primary regimen, with modest increases in nAb GMTs at Week 2 (5.1 and 4.8, respectively) that further increased at Week 4 (7.2 and 7.5). Two weeks after the second primary vaccination (at Week 6) (2xMVA-BN) nAb GMTs peaked (45.6) before stabilizing at Week 8 (34.0). In both the 1x and 2xMVA-BN groups, the nAb levels were near baseline 2 years after primary vaccination. After the MVA-BN boost at 2 years, both groups exhibited rapid anamnestic responses with nAb GMTs that peaked 2 weeks post-boost (80.7 and 125.3), at higher levels than those observed at any timepoint following primary vaccination, remaining elevated at 6 months post-boost (25.6 and 49.3). These anamnestic responses support the presence of durable immunological memory in both groups. No safety concerns were identified and the most common adverse event following a 2-year MVA-BN boost was injection site erythema in 82.2% of participants. Conclusion A single dose of MVA-BN elicits a durable memory immune response for at least 2 years. Similarly, high nAb responses following a boost dose among subjects in the initial 1xMVA-BN or 2xMVA-BN groups indicate that the approved 4-week interval of the two-dose regimen could optionally be extended up to at least 2 years. NCT00316524 and NCT00686582 Disclosures Heinz Weidenthaler, MD, Bavarian Nordic GmbH: Employee and received warrants Florian Lienert, PhD, Bavarian Nordic GmbH: employee Employee and received warrants Daniela Reichhardt, PhD, Bavarian Nordic A/S: employee Employee and received warrants Darja Schmidt, Dr, Bavarian Nordic GmbH: Employee and received warrants Günter Silbernagl, MSc, Bavarian Nordic: Employed|Bavarian Nordic GmbH: employee Employee and received warrants Paul Chaplin, PhD, Bavarian Nordic A/S: employee (CEO)|Bavarian Nordic A/S: Stocks/Bonds.

Background: Varicella, caused by the varicella-zoster virus, is a highly contagious infectious disease with substantial health and economic burden to society. Universal varicella vaccination (UVV) is not yet recommended by the Swiss National Immunization Program, which instead recommends catch-up immunization for children, adolescents and adults 11-40 years of age who have no reliable history of varicella or are varicella-zoster virus-IgG seronegative. The objective of this study was to perform an assessment of health impact and cost-effectiveness comparing UVV with current practice and recommendations in Switzerland. Methods: A dynamic transmission model for varicella was adapted to Switzerland comparing 2 base-case schedules (no infant vaccination and 10% coverage with infant vaccination) to 3 different UVV schedules using quadrivalent (varicella vaccine combined with measles-mumps-rubella) and standalone varicella vaccines administered at different ages. Modeled UVV coverage rates were based on current measles-mumps-rubella coverage of approximately 95% (first dose) and 90% (second dose). Direct medical costs and societal perspectives were considered, with cost and outcomes discounted and calculated over a 50-year time horizon. Results: UVV would reduce the number of varicella cases by 88%-90%, hospitalizations by 62%-69% and deaths by 75%-77%. UVV would increase direct medical costs by Swiss Franc (CHF) 39-49 (US $43-54) per capita and costs from a societal perspective by CHF 32-40 (US $35-44). Incremental quality-adjusted life-years per capita increased by 0.0012-0.0014. Incremental cost-effectiveness ratios for the UVV schedules versus the base-case were CHF 31,194-35,403 (US $34,452-39,100) per quality-adjusted life-year from the direct medical cost perspective and CHF 25,245-29,552 (US $27,881-32,638) from the societal perspective. Conclusions: UVV appears highly effective and cost-effective when compared with current clinical practice and recommendations in Switzerland from both a direct medical costs perspective and societal perspective.

Abstract Background An infection with high-risk human papillomavirus (HPV) is the obligatory aetiological factor for the development of cervical cancer. In Switzerland, the prevention strategy for cervical cancer is based on primary prevention via HPV vaccination and secondary prevention with an opportunistic screening programme for precancerous lesions. Vaccination is recommended to 11–26 years old male and female persons. The objective of the study was to assess the epidemiological impact on cervical cancer of switching from the currently implemented programme with the 4-valent vaccine to the 9-valent vaccine, in an 11–26 years old gender-neutral vaccination programme in Switzerland. Methods A previously validated dynamic transmission model of HPV infections was adapted and calibrated to the Swiss setting assuming an 80% coverage rate in HPV-vaccination and lifelong vaccine type-specific protection. A gender-neutral vaccination programme (males and females) for 11–26 years old with a 9-valent HPV vaccine was compared with the current 11–26 years old gender-neutral 4-valent vaccination programme. Sensitivity analyses were conducted in order to test the impact of lower vaccination coverage rates and a shorter duration of protection on the model outcomes. Results In Switzerland, a 9-valent gender-neutral vaccination programme would result in an additional prevention of 2979 cervical cancer cases, 13,862 CIN3 and 15,000 CIN2 cases, compared with the 4-valent gender-neutral vaccination programme over 100 years. These additional disease cases avoided would correspond to a 24, 36 and 48% cumulative incidence decrease in cervical cancer, CIN3 and CIN2 cases, respectively. It would also prevent additional 741 cervical cancer-related deaths over 100 years. A substantial additional reduction in cervical cancer and precancerous lesions burden is still observed when varying the vaccination coverage rate from 30 to 60% or reducing the duration of protection from lifelong to 20 years. Conclusions The switch to the 9-valent vaccine in Switzerland to prevent cervical diseases showed an important contribution in terms of public health impact compared with the 4-valent vaccine in an 11–26 years old gender-neutral population, even with very conservative assumptions such as low coverage rates or low duration of protection and limiting analysis to only cervical disease.