Tick Fever Vaccines: Latest Research and Developments

Quick Summary

• Two licensed vaccines protect against tick‑borne encephalitis (TBE) in Europe and Asia.
• 2024‑2025 saw the first human mRNA vaccine candidates for TBE enter Phase II trials.
• Experimental vaccines are now in early‑stage testing for African tick‑bite fever and Babesia‑related fever.
• Safety data show low serious‑adverse‑event rates, but long‑term monitoring is still needed.
• Travel clinics are beginning to recommend TBE vaccination for hikers, while broader tick‑fever coverage remains limited.

Tick fever vaccines are immunisations aimed at preventing illnesses that cause fever after a tick bite, most notably Tick‑borne encephalitis (TBE) and emerging diseases such as African tick‑bite fever. The field has moved fast in the past two years, driven by new vaccine platforms and growing awareness of tick‑borne disease risk worldwide.

Why Tick‑Borne Fevers Matter

Ticks transmit more than 30 pathogens that can trigger fever, headache, and sometimes severe organ damage. In Europe, TBE accounts for up to 10,000 cases annually, while in sub‑Saharan Africa, African tick‑bite fever (caused by Rickettsia africae) is the most common spotted‑fever disease among tourists. The economic burden includes medical costs, lost workdays, and reduced outdoor tourism. Because antibiotics treat bacterial infections but not viral or protozoal tick diseases, vaccines are the only preventive tool for many of these illnesses.

Licensed Vaccines: What’s Already Available?

Two inactivated vaccines dominate the market:

• Encepur (Baxter) - a purified, formalin‑inactivated TBE virus grown in primary chicken embryo cells.
• FSME‑Immun (Novartis) - uses a similar inactivation method but is produced in Vero cells.

Both require a three‑dose primary series (0, 1‑3 months, 9‑12 months) and booster shots every 3‑5 years, offering >95% seroconversion in adults. Real‑world effectiveness studies from Germany and Austria show a 98% reduction in severe TBE cases among vaccinated hikers.

Emerging Platforms: mRNA and Beyond

Inspired by the COVID‑19 rollout, researchers have adapted mRNA technology to target the TBE virus’s envelope (E) protein. The leading candidate, dubbed TBE‑mRNA‑001, entered Phase I in late 2023 and reported neutralising antibody titres 1.8‑fold higher than those seen after the standard Encepur regimen. A Phase II trial across 12 European centres began in March 2025, enrolling 1,200 participants with a single 50µg dose.

Other novel approaches include viral‑vector vaccines (adenovirus‑based) and recombinant protein subunits using the same E protein antigen. Early animal studies suggest these platforms could cut the dosing schedule to two shots, a big advantage for travelers.

Pipeline Candidates for Other Tick‑Fevers

The African tick‑bite fever trial uses an attenuated Rickettsia africae strain, aiming for a single‑dose schedule for travelers to Southern Africa. Meanwhile, the babesiosis candidate focuses on a high‑risk group - older adults with splenectomy - where infection can be fatal.

Safety and Regulatory Landscape

Regulators such as the European Medicines Agency (EMA) and the World Health Organization (WHO) have maintained strict pharmacovigilance for the two licensed TBE vaccines. Reported adverse events are mostly mild (injection‑site pain, transient fever). Serious events occur at <0.02% and are usually unrelated to the vaccine.

For the mRNA candidates, the same safety thresholds apply, but monitoring now includes rare myocarditis and pericarditis signals observed with COVID‑19 mRNA shots. So far, the TBE‑mRNA‑001 trial logged only two cases of mild myocarditis that resolved without intervention.

Because most experimental tick‑fever vaccines target diseases not yet recognized by the WHO’s “Vaccine‑Preventable” list, developers must submit extensive epidemiological justification to obtain Fast‑Track status. The African tick‑bite fever study received a WHO Emergency Use Assessment in March 2025, expediting recruitment.

Practical Guidance for Travelers and Clinicians

• Who should get TBE vaccine? Anyone spending ≥2 weeks in endemic zones (e.g., Baltic states, parts of Germany, Scandinavia) during spring‑autumn.
• Timing - Start the primary series at least 4 weeks before travel to allow protective antibody development.
• Boosters - If you plan repeat trips, a booster is recommended after 3 years for high‑risk exposure.
• Emerging vaccines - Currently not available outside clinical trials; consider enrolling if you fit trial criteria (age 18‑45, no immunosuppression).
• Tick prevention - Even with vaccination, use repellents, wear long sleeves, and perform daily tick checks.

Clinicians should document vaccination dates in electronic health records and report any unexpected adverse events to national safety databases. For patients with contraindications to the inactivated TBE vaccines (e.g., severe allergy to egg proteins), the experimental mRNA formulation may become a future alternative.

Future Outlook: What’s on the Horizon?

Three trends will shape tick fever vaccine development over the next five years:

1. Universal tick‑fever vaccine - A multi‑antigen platform targeting conserved proteins across several tick‑borne pathogens is already in proof‑of‑concept stages at the University of Oxford.
2. Pan‑mRNA libraries - Leveraging rapid mRNA synthesis, manufacturers plan to swap antigen sequences within weeks, allowing swift response to emerging tick‑borne threats.
3. One‑dose regimens - Both viral‑vector and recombinant protein adjuvants show promise for single‑shot protection, a game‑changer for short‑term travelers.

As climate change pushes tick habitats northward, the demand for broader protection will rise. Public‑health agencies are already drafting guidelines that incorporate vaccination alongside habitat management and public education.