Across 101 unique vaccine Phase I–III trials, the leading named site is Universitair Ziekenhuis Gent with 13/101 trials (12.9%). Spain has the broadest country site footprint with 310/1,488 site allocations (20.8%), while France carries the largest planned participant allocation with 5,323/33,285 participants (16.0%). Disease clustering is led by respiratory syncytial virus infection with 9/101 trials (8.9%), while Infectious Disease is the dominant therapy area with 52/101 trials (51.5%).
Universitair Ziekenhuis Gent ranks first with 13/101 trials (12.9%). The next strongest named sites are Hospital Universitario La Paz and Hospital Universitario 12 De Octubre, each appearing in 11/101 trials (10.9%).
The site leaderboard is not dominated by one country alone. Belgium contributes the top site, but Spain supplies four of the ten most recurrent named sites, showing a broad repeat-site network for vaccine trial delivery.
Spain leads site footprint with 310/1,488 site allocations (20.8%), followed by France with 285 (19.2%) and Germany with 205 (13.8%). Participant allocation is more balanced: France leads with 5,323/33,285 participants (16.0%), followed by Germany with 4,286 (12.9%), Poland with 4,256 (12.8%), Belgium with 3,960 (11.9%), and Spain with 3,488 (10.5%).
| Country | Sites | Site share | Participants | Participant share | Trials |
|---|---|---|---|---|---|
| Spain | 310 | 20.8% | 3,488 | 10.5% | 32 |
| France | 285 | 19.2% | 5,323 | 16.0% | 30 |
| Germany | 205 | 13.8% | 4,286 | 12.9% | 32 |
| Poland | 127 | 8.5% | 4,256 | 12.8% | 18 |
| Belgium | 98 | 6.6% | 3,960 | 11.9% | 27 |
| Italy | 91 | 6.1% | 485 | 1.5% | 14 |
| Finland | 86 | 5.8% | 3,296 | 9.9% | 11 |
| Greece | 42 | 2.8% | 424 | 1.3% | 7 |
| Bulgaria | 38 | 2.6% | 806 | 2.4% | 5 |
| Estonia | 32 | 2.2% | 1,623 | 4.9% | 8 |
Spain is the broadest operational site market, but France, Germany, Poland, and Belgium carry heavier participant allocation relative to their site counts. This suggests different country roles: Spain provides network breadth, while France and Germany anchor higher-volume planned enrollment.
Phase III is the largest segment with 37/101 trials (36.6%), 951/1,488 site allocations (63.9%), and 23,750/33,285 participants (71.4%). Earlier development remains substantial: Phase I and Phase I/II together account for 36/101 trials (35.6%).
The vaccine site market is late-stage heavy by operational load. Phase III accounts for just over one-third of trials but nearly two-thirds of all site allocations and more than seven-tenths of planned participants.
Infectious Disease dominates with 52/101 trials (51.5%), 608 site allocations, and 22,397 planned participants. Oncology is the second-largest therapy area with 32/101 trials (31.7%) and 578 site allocations, showing that vaccine trial activity is split between prevention/infectious-disease programs and therapeutic cancer vaccine programs.
Respiratory syncytial virus infection is the largest disease cluster by trial count with 9/101 trials (8.9%) and 12,251 planned participants. Allergy-related vaccine programs form several smaller but repeated clusters, while oncology contributes breadth rather than a single dominant disease label.
Paediatric trials represent 24/101 trials (23.8%) but account for 394/1,488 site allocations (26.5%) and 10,507/33,285 participants (31.6%). Orphan-designated vaccine records are rare, appearing in 2/101 trials (2.0%).
Paediatric vaccine trials carry a larger share of participants than their trial count would suggest, indicating that child-focused vaccine programs are operationally meaningful even though they are a minority of the cohort.
Site allocation means the country-level number of sites reported for a trial-country record. Participant allocation means the country-level planned participant count reported for a trial-country record. Site participation means the number of unique trial codes in which a normalized site name appears.