Clinical trials
Clinical trials are a central component of medical research. They systematically evaluate new medicines, vaccines, and therapeutic approaches in order to scientifically assess their safety and efficacy.
On this page, you can learn how clinical trials work and why they are important for healthcare.
In Switzerland, MSD coordinates around 50 clinical trials every year.
What is a clinical trial?
A clinical trial is a scientific study conducted in humans—with voluntary participation and under strictly controlled conditions.
he aim of a clinical trial is to examine in detail:
- how a new medicine, vaccine, or other treatment works,
- whether the treatment is safe and how well it is tolerated,
- what side effects may occur, and
- what dosage is appropriate.
The results of a clinical trial form the basis for assessment by regulatory authorities and are decisive in determining whether a medicine is approved for use.
Every clinical trial follows a clearly defined study protocol
The study protocol describes:
- the objectives of the trial,
- who is eligible to participate,
- how the treatment is administered,
- what data will be collected, and
- how safety is monitored.
The study plan is also referred to as the “protocol”.
Why are clinical trials important?
Clinical trials drive medical progress. They help ensure that:
- new treatment options can be developed,
- the safety and efficacy of therapies are scientifically demonstrated,
- existing treatments can be improved, and
- better healthcare can be achieved in the long term.
For patients with no or limited remaining treatment options, taking part in a clinical trial may provide an additional opportunity.
How does a clinical trial work?
Every clinical trial goes through three key stages: the information and screening phase, the treatment phase, and the follow-up phase.
1. Information and screening phase
The information and screening phase determines whether a person is eligible and willing to participate in a clinical trial.
- The study team provides written and verbal information about the objectives, procedure, potential benefits, and risks of the clinical trial.
- Medical examinations are carried out to determine whether participation is medically appropriate and safe.
- Participation only begins once all questions have been answered and written consent has been obtained.
This phase ensures that participants are well informed and can make a voluntary decision.
2. Treatment phase
During the treatment phase, participants receive the therapy specified in the study protocol. For example a medicine, a vaccine, or a combination of several therapies.
Typical elements of this phase are:
- regular doctor’s appointments and check-up examinations,
- imaging procedures or other tests,
- completing questionnaires or keeping a diary, and
- documentation of possible side effects.
The study team closely monitors the patient’s health and adjusts the treatment as necessary.
3. Follow-up phase
Once the active treatment has been completed, the follow-up phase of the clinical trial begins.
During this phase, the team continues to monitor:
- how the participants’ health develops,
- whether the effect of the treatment is confirmed, and
- whether any long-term effects or late side effects occur.
Follow-up is essential to obtain a complete picture of the safety and efficacy of a therapy. The data obtained in this way is included in the final evaluation of the clinical trial.
Who can participate in a clinical trial?
There are inclusion and exclusion criteria for each study. These ensure that:
- participation is medically appropriate,
- safe, and
- scientifically meaningful.
Treating physicians can assess whether a trial is suitable for a patient.
Study centers provide detailed information about requirements and procedures.
Who conducts clinical studies?
Clinical trials are conducted by experienced, qualified teams. These include:
- investigators (physicians with experience in clinical research),
- study coordinators,
- nursing staff,
- scientific staff.
They ensure that the clinical trial is conducted in accordance with applicable legal requirements, the principles of Good Clinical Practice (GCP), and ethical guidelines.
Safety, ethics, and transparency in clinical trials
The protection of participants is a top priority.
Before a clinical trial can begin, authorities and ethics committees review:
- the scientific basis of the trial,
- the risk-benefit ratio,
- compliance with legal requirements, and
- the information documents for participants.
Throughout the entire duration of the trial, regular checks are carried out to ensure that the clinical trial can continue to be conducted responsibly. All safety-related events are documented and medically evaluated.
Clinical trials are conducted in accordance with the international standards of Good Clinical Practice (GCP) – a globally recognized quality framework for clinical research.
Study search
To search for clinical trials in Switzerland, the Federal Office of Public Health (FOPH) provides the HumRes platform.
There you can find out
- whether studies are currently being conducted on a specific disease,
- whether participants are still being recruited, and
- which study centers are responsible for providing further information.
To the platform: www.humanforschung-schweiz.ch
Clinical trials at MSD in Switzerland
Switzerland is one of more than fifty countries in which MSD conducts clinical research.
Our team at the Citybay site in Lucerne coordinates around fifty clinical trials in Switzerland every year – currently in the fields of oncology, infectious diseases, immunology, and general medicine (as of 07/2025).
CH-NON-03186, 11/2025