The long-term efficacy of tick-borne encephalitis vaccines available in Europe - a systematic review

Persistence of Tick-Borne Encephalitis Virus in Goat and Cow Milks Under Different Storage Conditions and Following Thermal Inactivation

Tick-borne encephalitis virus (TBEV) is a neuroinvasive arbovirus that is primarily transmitted to humans through the bites of Ixodes ricinus ticks. Consumption of unpasteurised milk and dairy products from infected ruminants can also cause infection in humans. In the majority of food-borne TBE (FB-TBE) cases, goat milk and/or cheese has been identified as the source of infection. The aim of the present study was to analyse the persistence of the infectious strain TBEV_Ain_2020 virus in spiked goat and cow raw milks under different storage conditions, and following pasteurisations performed at 63 °C/30 min or 72 °C/15 s. The total genome of TBEV was stable up to 48 h in goat and cow's milks at 4 °C and 21 °C. In contrast, the viral titre was significantly lower in goat milk from T + 2 h post-contamination up to 17 h compared to culture cell medium and cow milk at 4 °C. At 21 °C, viral titres were lower than in DMEM in both milks up to T + 12 h. Thermal inactivations were effective in goat milk, but were not sufficient to eliminate all infective virus particles in cow milk. These unexpected findings highlighted that pasteurisation processes should be adapted to the species of origin of the milk and to the initial viral load to ensure food safety.

Severe Cases of Tick-Borne Encephalitis in Northeastern Poland

Tick-borne encephalitis (TBE) is the most prevalent viral infection of the central nervous system (CNS) in Poland. The disease is characterized by the presence of two stages. The first phase, called the viremic stage, presents with flu-like symptoms, while the second stage of TBE is characterized by damage to the nervous system and may follow a severe and dramatic course. The aim of this paper is to increase the awareness of the potential sequelae after TBE. In this study, we report cases of severe TBE in 36-year-old and 57-year-old female patients. The outcome of TBE varies from patient to patient, but there are some factors that can help to predict the severity of TBE infection. The risk factors presented in these patients were as follows: the monophasic course of TBE, high pleocytosis in cerebrospinal fluid (CSF) and older age. Both of our patients were not vaccinated despite the World Health Organization's (WHO's) recommendations. Both patients had no history of travel outside their region of residence prior to the onset of illness. The few risk factors shown in our patients and the serious sequelae of the disease may indicate the need to test patients for possible gene mutations.

Evaluating the specificity of flavivirus proteases in Aedes aegypti cells for dengue virus 2-derived cleavage sites

Flaviviruses are a diverse group of RNA viruses known for their significant impact on human health worldwide. We generated a series of reporters that included cleavage sequences from the dengue virus type 2 polyprotein and co-transfected with plasmids encoding various flavivirus proteases into Aedes aegypti cells, followed by fluorescent imaging and western blot analysis for the determination of proteolytic cleavage. Recombinant flavivirus NS2B3 proteases from medically significant and insect-specific flaviviruses were able to process reporters encoding cleavage sequences from the dengue virus type 2 polyprotein in vitro including proteases from dengue virus types 1-4, Zika virus, yellow fever virus, Aedes flavivirus, and cell-fusing agent virus. Reporters were not cleaved when transfected cells were infected with dengue virus type 2. Endoplasmic reticulum tethered reporters were also cleaved by protease alone but not by infectious virus. These results shed light on the ability of multiple flavivirus proteases to cleave sequences derived from outside of their genome and raise new questions concerning the requirements for effective cleavage by flavivirus proteases in trans.

Special Issue: "Vaccination and Global Health"

This Special Issue, titled 'Vaccination and Global Health,' compiles 11 broad-ranging papers, each exploring critical facets of vaccination, public health, and global healthcare systems [...].

What makes patients tick? Vaccine preferences against tick-borne encephalitis in four European countries

BACKGROUND

We explored vaccine motivation and preferences for tick-borne encephalitis (TBE) vaccine attributes among participants in TBE-endemic countries in Europe.

METHODS

An online survey was conducted among the general public in Austria, Germany, Switzerland, and Sweden. Participants were ≥ 18 years old, open to receiving vaccines, and living in, or regularly traveling to, TBE-endemic regions in the aforementioned countries. Participants were asked about their general vaccine knowledge and motivations for vaccination, before rating the importance of TBE vaccine attributes, such as efficacy, safety, dosing schedule, and booster interval. Thereafter, participants were shown three hypothetical TBE vaccine profiles with different combinations of attributes. Assuming equal efficacy and safety, participants were asked to select their preferred profile from 12 screens as part of a discrete-choice conjoint analysis. Utility scores were calculated to show the importance of each attribute. Data are presented for the overall survey group and by age and gender, using t-tests to compare means.

RESULTS

For 73% of participants (n = 1003/1379), self-protection was among the top three reasons to get vaccinated. Disease severity, protection of children or family, and advice or recommendation from a doctor/healthcare professional (HCP) were top three reasons for over half of participants. The majority (58-69%) agreed or strongly agreed that they trust their doctor/HCP on the subject of vaccines, they rely on their doctor/HCP's vaccine knowledge, and they prefer their doctor/HCP to make recommendations on which vaccines they or their families should take. Efficacy and safety were the most important standalone TBE vaccine attributes; however, among TBE vaccine profiles including 3-, 5- and 10-year booster intervals, the 10-year booster interval was the most influential attribute level when choosing a preferred vaccine profile (utility score: 0.58 [standard error: 0.01]). Differences in motivators and preferences were observed between age and gender subgroups.

CONCLUSION

The high level of doctor/HCP reliance highlights the key role doctors/HCPs play in influencing vaccine decision-making. Booster interval was the biggest driver of choice when selecting a hypothetical TBE vaccine profile, with the strongest preference for a 10-year booster interval. These findings could be used to inform TBE vaccination recommendations and in the further development of TBE vaccines.

Adult-Onset Encephalitis over Twelve Years in Easternmost Finland

INTRODUCTION

The epidemiology of encephalitis varies by region and time. Available Finnish data are outdated and there are no data from eastern parts of the country nor concerning the occurrence of autoimmune encephalitides.

MATERIALS AND METHODS

Patients with encephalitis were identified from mandatory administrative registries in North Karelia Central Hospital. The diagnoses were verified and data extracted by reviewing the patient records. Study period was 2010-2021. Only patients >16 years of age were included.

RESULTS

Fifty-one patients with a clinical encephalitis were identified (55% men) with a median age of 65 years (interquartile range 45, 73; total age range 16-88 years) indicating a crude incidence of 3.1/100,000 person-years for the entire study period. A specific aetiology could be identified in 31 cases (61%) with tick-borne encephalitis (TBE) being the most common one (20% of all 51 cases), followed by herpes simplex virus type 1 (HSV-1, 16%) and varicella zoster virus (VZV, 14%). Autoimmune aetiology was confirmed in 10%. TBE was most often found in the youngest age group (16-52 years of age) and the herpes viruses in the oldest group (71 years or older). A specific cause was most often identified in the oldest patients (78%). TBE patients were younger than patients with VZV (p = 0.0009) or HSV-1 (p = 0.0057), but there was no difference when they were compared to patients with autoimmune (p = 0.27) or unknown (p = 0.074) aetiology. At presentation, there were differences in the occurrence of some clinical signs and symptoms between aetiologies but nothing specific. Eight patients (16%) were immunosuppressed. Inpatient seizures occurred in 10 patients (20%). In these cases, the aetiology was HSV-1 in 50% and TBE or VZV in none. A full recovery was observed in 51% of all patients while 3 patients (6%) had died of the encephalitis while in hospital or shortly after discharge.

CONCLUSIONS

Adult-onset encephalitis was more common and the patients older in easternmost Finland than previously reported in other parts of the country. TBE, HSV-1, and VZV are the most commonly identified specific aetiologies whereas a fifth of the cases are probably caused by autoimmunity. Prognosis depended on aetiology but was very good in the majority of cases.

Advancements in Vaccine Strategies for Chronic Liver Disease Patients: Navigating Post-COVID Challenges and Opportunities

This review addresses the vital role of vaccinations in managing patients with chronic liver disease (CLD), especially in the context of the post-COVID-19 landscape. The pandemic has highlighted the unique vulnerabilities of CLD patients, including those awaiting liver transplantation and post-transplant individuals, who face heightened risks of infection due to compromised immune responses. Recent advancements in vaccine technology, such as mRNA platforms, novel adjuvants, and advanced delivery systems, have significantly accelerated vaccine development, enhancing both speed and efficacy. Moreover, the emergence of personalized vaccines, tailored to everyone's unique immunological profile, presents new opportunities, particularly for those with chronic conditions. This review synthesizes the current state of evidence regarding vaccine recommendations for CLD patients, focusing on their response to vaccinations and proposing effective strategies to protect this vulnerable group from vaccine-preventable diseases. It also explores the challenges in implementing these strategies and considers the impact of emerging vaccine delivery systems on improving outcomes for CLD patients. The paper aims to provide nuanced guidance on vaccination in the rapidly evolving healthcare landscape, addressing both technological innovations and comprehensive patient care strategies.

Defining the "Correlate(s) of Protection" to tick-borne encephalitis vaccination and infection - key points and outstanding questions

Tick-borne Encephalitis (TBE) is a severe disease of the Central Nervous System (CNS) caused by the tick-borne encephalitis virus (TBEV). The generation of protective immunity after TBEV infection or TBE vaccination relies on the integrated responses of many distinct cell types at distinct physical locations. While long-lasting memory immune responses, in particular, form the basis for the correlates of protection against many diseases, these correlates of protection have not yet been clearly defined for TBE. This review addresses the immune control of TBEV infection and responses to TBE vaccination. Potential correlates of protection and the durability of protection against disease are discussed, along with outstanding questions in the field and possible areas for future research.