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Condition (MeSH)

Encephalitis

ClinicalTrials.gov lists 317 trials for Encephalitis or a narrower condition beneath it. Pfizer has the most among industry and government lead sponsors, with 20.

MeSH D004660 Nervous System Diseases C10 Listed by Orphanet as a rare disease
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Phase 1 Phase 1 29 Phase 1/2 Phase 1/2 5 Phase 2 Phase 2 55 Phase 2/3 Phase 2/3 5 Phase 3 Phase 3 45 Phase 4 Phase 4 36 Not applicable Not applicable 41 Observational Observational 100 Phase 1 Phase 1 29 Phase 1/2 Phase 1/2 5 Phase 2 Phase 2 55 Phase 2/3 Phase 2/3 5 Phase 3 Phase 3 45 Phase 4 Phase 4 36 Not applicable Not applicable 41 Observational Observational 100

Trials per phase (log scale)

1 more section with rows

116 of the 317 trials are tagged with Encephalitis itself; the rest are tagged with a narrower condition beneath it.

Get the Encephalitis report as a PDF

The PDF carries up to 50 rows of each section, where the page shows the first few, with the sources listed. Enter a work email and confirm it from the message we send, and the report follows by email.

When did Encephalitis trials start? (29)

Shown in this order: most recent first, 1990 onwards. 2026 is partial: trials registered with a 2026 start date so far, not a full year.

Trials over time, by phase

  • Phase 1
  • Phase 1/2
  • Phase 2
  • Phase 2/3
  • Phase 3
  • Phase 4
  • Not applicable
  • Observational

Top of scale: 22

1997: 1 trials (Observational 1) 1998: 1 trials (Phase 2/3 1) 2000: 1 trials (Phase 3 1) 2001: 2 trials (Phase 3 1, Phase 2 1) 2002: 7 trials (Phase 3 2, Phase 2/3 1, Phase 2 4) 2003: 4 trials (Observational 1, Phase 2 2, Phase 1/2 1) 2004: 6 trials (Observational 1, Phase 4 2, Phase 2 2, Phase 1 1) 2005: 22 trials (Observational 2, Phase 4 3, Phase 3 8, Phase 2 4, Phase 1 5) 2006: 8 trials (Observational 1, Not applicable 1, Phase 4 1, Phase 3 3, Phase 1 2) 2007: 12 trials (Observational 2, Phase 4 4, Phase 3 2, Phase 2 3, Phase 1 1) 2008: 12 trials (Observational 1, Not applicable 1, Phase 4 1, Phase 3 3, Phase 2 5, Phase 1 1) 2009: 10 trials (Observational 1, Phase 4 2, Phase 3 3, Phase 2 3, Phase 1/2 1) 2010: 14 trials (Observational 3, Phase 4 2, Phase 3 9) 2011: 6 trials (Observational 1, Phase 3 2, Phase 2/3 1, Phase 2 1, Phase 1 1) 2012: 10 trials (Observational 2, Not applicable 1, Phase 4 5, Phase 3 1, Phase 1 1) 2013: 11 trials (Observational 3, Not applicable 2, Phase 4 3, Phase 3 1, Phase 2 1, Phase 1 1) 2014: 13 trials (Observational 6, Not applicable 3, Phase 4 1, Phase 3 1, Phase 2 1, Phase 1/2 1) 2015: 15 trials (Observational 4, Not applicable 1, Phase 4 4, Phase 3 2, Phase 2/3 1, Phase 2 3) 2016: 8 trials (Observational 3, Not applicable 1, Phase 4 1, Phase 3 1, Phase 1/2 1, Phase 1 1) 2017: 11 trials (Observational 6, Not applicable 1, Phase 3 1, Phase 2 2, Phase 1 1) 2018: 8 trials (Observational 2, Not applicable 2, Phase 4 1, Phase 3 1, Phase 2 1, Phase 1 1) 2019: 14 trials (Observational 9, Not applicable 2, Phase 2 1, Phase 1 2) 2020: 16 trials (Observational 10, Not applicable 3, Phase 4 1, Phase 2 2) 2021: 17 trials (Observational 7, Not applicable 4, Phase 4 1, Phase 3 1, Phase 2 2, Phase 1 2) 2022: 13 trials (Observational 9, Not applicable 2, Phase 2 2) 2023: 14 trials (Observational 8, Not applicable 3, Phase 4 1, Phase 2 1, Phase 1 1) 2024: 16 trials (Observational 5, Not applicable 2, Phase 4 3, Phase 3 2, Phase 2/3 1, Phase 2 2, Phase 1 1) 2025: 15 trials (Observational 5, Not applicable 3, Phase 2 4, Phase 1/2 1, Phase 1 2)

Trials registered with a start date in each year, 1990 onward, stacked by phase (complete years only; the current partial year is in the table's notes). The table below lists the same counts, most recent years first.

Trials started per year
Year Trials started
2026 (partial year) 15
2025 15
2024 16
2023 14
2022 13
2021 17
2020 16
2019 14
2018 8
2017 11

Forecast of the full-year count, planned starts included, not rows of this table: about 16 trials starting in 2026 and about 16 in 2027, the average of the 24 months through September, counted as registered and carried forward. The rows of this table count trials registered so far with a start date in the year, planned starts included; the forecast looks ahead to the count for the whole year, so it is not the same measure. In backtests on conditions of this size, forecasts made part-way through the year were typically off by about 28 percent and ran about 20 percent low against the count later registered; forecasts made before the year began were off by about 39 percent and ran about 37 percent low against the count later registered. These figures rest on a few years of history (target years from 2018 to 2025, varying by figure), place each condition as it is mapped today rather than as it was then, and score against a count for the newest year that was still being revised. Only condition series were scored.

Prediction, not a registry value: median of 36 months from start to primary completion across 15 trials still running at the 2026-10-09 snapshot; registered median of 20 months across 172 trials with a primary completion typed Actual. Source: ClinicalTrials.gov / AACT (CTTI), public domain.

What phase are Encephalitis trials in? (9)

Shown in this order: phase order.

Show the trials by phase as a table
Trials by phase
Phase Trials
Phase 1 29
Phase 1/2 5
Phase 2 55
Phase 2/3 5
Phase 3 45
Phase 4 36
Not applicable 41
Observational 100
Expanded access 1

How many Encephalitis trials are recruiting? (10)

Shown in this order: the order a trial moves through, from not yet recruiting to unknown.

Trials by recruitment status
Status Trials
Not yet recruiting 14
Recruiting 38
Enrolling by invitation 1
Active, not recruiting 5
Completed 188

Status as registered on ClinicalTrials.gov. Each trial is counted once.

Which lead sponsors run the most Encephalitis trials? (9)

Shown in this order: most trials first. Lead sponsors the registry classes as industry, NIH, US federal, other government or network. A hospital or university the registry files as government can appear here. Sponsors it classes as academic or other are shown on the full page, because that class cannot separate an institution from a named investigator.

Lead sponsors
Sponsor Trials
Pfizer 20
National Institute of Allergy and Infectious Diseases (NIAID) 17
Valneva Austria GmbH 17
Sanofi Pasteur, a Sanofi Company 13
Sanofi 7

Which drugs are being tested for Encephalitis? (5)

Shown in this order: most trials first. One row per drug, matched to a single molecule under all its names, ranked by number of trials.

Drugs tested
Drug Trials
IC51 17
Pyrimethamine 6
Calcium Leucovorin 4
Zidovudine 3
Yellow Fever Vaccine 3

Interventions as named in the registry (10)

Shown in this order: most trials first.

Interventions as named in the registry
Drug Trials
Tick-Borne Encephalitis (TBE) Vaccine (Inactivated) 13
IMOJEV 4
Japanese Encephalitis purified inactivated vaccine 3
ART5803 3
Dexamethasone/Dexamethasone acetate 3

These are the names sponsors entered on ClinicalTrials.gov that we have not matched to a single molecule. Some are drugs under a brand or code name; others are procedures, doses or arm labels.

Which serious adverse events do Encephalitis trials report? (10)

Shown in this order: most subjects affected first. Subjects affected summed across trials, a cross-trial signal, not a rate.

Serious adverse events in this condition's trials
Adverse event Subjects affected Trials
Gastroenteritis 104 14
Pneumonia 84 15
Febrile convulsion 59 10
Bronchitis 39 7
Viral infection 22 5

Which publications cover Encephalitis? (263)

Shown in this order: major-topic papers first, then newest, then most linked to trials.

Rare-disease identity (2)

Shown in this order: exact, broader, narrower, other.

Rare-disease identity
Orphanet disease ORPHA code Relation Source
Encephalitis 97275 Exact Orphadata Science knowledge files, Product 1
Encephalitis 97275 Exact Orphanet Rare Disease Ontology (ORDO)

Sub-conditions in MeSH (5)

MeSH descendants one level down with at least one trial, most trials first.

Not on this page

Not measured: delivery record.

Checked, with nothing recorded for this condition: prevalence.

Browse all condition evidence pages