[RobertKoch]

@dickatlee — your friends are asking the right question at the right time, and the fact that they’re not reflexively accepting the recommendation is the right instinct. A few things worth knowing as they think it through.

The vaccine itself. TICOVAC (Pfizer, FDA-approved August 13, 2021 — package insert at https://www.fda.gov/media/151502/download) is the U.S.-labeled name for what’s been sold in Europe for decades as FSME-IMMUN (Pfizer/Baxter lineage). It’s the same product. The other European TBE vaccine is Encepur (Bavarian Nordic, formerly GSK). Both are inactivated whole-virus vaccines, not mRNA, not adenovirus-vector. They’re conventional vaccine technology that’s been in continuous use in Austria, Germany, the Czech Republic, Switzerland, the Baltics, and Slovenia since the 1970s. Pediatric formulations (FSME-Immun Junior, Encepur Children) have been used at scale since the 1980s.

Field-effectiveness data — the real numbers, not the press releases. Austria has the longest and best-documented record because it has the highest TBE vaccination coverage in Europe (~85% of the population). The Heinz et al. surveillance series (Vaccine 2007; updated 2013 in CDC’s Emerging Infectious Diseases, https://wwwnc.cdc.gov/eid/article/19/1/12-0458_article; refreshed again 2025) reports field effectiveness of roughly 96–99% against clinically apparent TBE in fully vaccinated individuals. Santonja et al. (2022, PMID 35235953) found vaccinated patients who do break through tend to have milder disease. These are observational, not RCT, but they’re large-population data over twenty-plus years. The “prone to failure” framing from the 2020 article you mentioned likely referred to specific cohorts (immunocompromised, elderly with waning immunity, or people with incomplete schedules) — not the general pediatric population.

What TBE actually does in children — and what it doesn’t. The base-rate question matters. Per ECDC (2022 epi report), the EU/EEA notification rate is 0.81 per 100,000 population per year — and that’s concentrated in specific endemic regions (Baltic states, Czechia, Slovenia, Austria, southern Germany, parts of Switzerland). Outside those zones the rate is functionally zero. CDC’s pediatric data (https://www.cdc.gov/tick-borne-encephalitis/hcp/clinical-signs/index.html): case fatality 1–20% depending on viral subtype (European subtype is the milder end of that range, Far Eastern is the lethal end at up to 35%); long-term neurological sequelae in 10–50% of clinical cases. Children generally do better than adults with TBE (Bogovic et al., PMC7438291) — but “better than adults” still includes documented long-term fatigue, cognitive issues, and behavioral changes affecting school performance (Sciencedirect 2023).

The honest framing. This is not a “should everyone everywhere get this” question. It’s a regional risk question: where does the family live, where do they hike/forest/farm, and what’s the local TBE incidence per 100,000? ECDC has a NUTS-region map of locally-acquired cases (https://www.ecdc.europa.eu/en/infectious-disease-topics/tick-borne-encephalitis/surveillance-and-updates/locally-acquired-tbe) that lets you look up the actual rate where your friends are.

If they’re in a hot zone (say, Styria in Austria, or southern Bohemia, or eastern Bavaria), the math is very different from someone in northern France or coastal Portugal where TBE is essentially absent.

The girl was bitten — what about post-exposure? TICOVAC and the European TBE vaccines are pre-exposure prophylactics. There is no post-exposure prophylaxis (PEP) for TBE that has been demonstrated effective in controlled studies. TBE-specific immunoglobulin was used historically in Austria but was withdrawn in the late 1990s after data suggested it might worsen outcomes in children (the “antibody-dependent enhancement” concern). So vaccinating now, weeks after a tick bite, doesn’t address the bite that already happened. It only protects against future exposures.

The real near-term action item. Watch the child for biphasic illness — TBE typically presents as a flu-like phase 7–14 days post-bite (fever, malaise, muscle aches), then a remission of about a week, then the neurological phase (high fever, headache, stiff neck, sometimes worse). If anything resembling that pattern develops in the next 4–6 weeks, get her to a clinician immediately. Most ticks don’t carry TBEV even in endemic areas; the per-bite transmission risk is low.

One more thing worth knowing. The Erber 2022 ecological study (PMC10515056) and the Tandfonline 2024 review found that the booster interval can safely extend to 10 years rather than the 3–5 year schedule the manufacturers recommend. If your friends do decide to vaccinate the girl, that’s worth knowing — the manufacturer’s schedule is more aggressive than the immunogenicity data require.

If they want a single resource to read on this, the ECDC factsheet (https://www.ecdc.europa.eu/en/tick-borne-encephalitis/facts/factsheet) and the CDC clinician page (linked above) are the cleanest non-marketing summaries I’ve seen. Both are upstream of the vaccine manufacturers.

[djoswald]

PLEASE DO NOT TAKE ANY VACCINE!

[IMA-HelenT]

Hi @dickatlee I will send this question to the team for tomorrow’s webinar .