Clinical Trials

ClinicalTrials.gov is a database of privately and publicly funded clinical studies conducted around the world. The website is maintained by the National Library of Medicine (NLM) and the National Institute of Health (NIH). Information on all outgoing trials in this registry includes a short description, the date of the beginning of the study, its ending time, the names of the organisers and the recruitment criteria. After being completed, results of the studies can be found on the National Library of Medicine website.


Information on ClinicalTrials.gov is provided and updated by the sponsor or principal investigator of the clinical study. We only publish studies registered by the developers and manufacturers of the COVID-19 vaccines, which are approved in the Republic of Ireland.

The majority of these studies are not completed and some are registered as being in the enrollment phase after the estimated finish date has passed. According to the U.S. Food and Drug Administration (FDA), clinical research requires an animal and toxicity study, followed by four phases of human trials.
Just to give an example of risks and the importance of the safety monitoring process:
Phase 1 usually takes several months after which an estimated 70% of medical products move on to the next phase. Phase 2 is up to two years long and only 33% of trials move forward from there to Phase 3 where approximately 25-30% of medical products successfully finish and proceed to the Phase 4. The majority of the population received multiple COVID-19 injections. We haven’t found any studies by manufacturers on the effects of multiple doses, (apart from the first booster/third dose), nor any studies of the effects on breastfeeding, or carcinogenicity.


Below is a list of trials by manufacturers of the vaccines, with estimated study completion date (ESCD), number of participants, dates of trial, and recruitment status. Data has last been updated by us in October 2022.