clinical trials ( is a Web-based resource that provides patients, their family members, health care professionals, researchers, and the public with easy access to information on publicly and privately supported clinical studies on a wide range of diseases and conditions. The Web site is maintained by the US Government National Library of Medicine (NLM) at the National Institutes of Health (NIH). Information on is provided and updated by the sponsor or principal investigator of the clinical study.

Clinical trial studies conducted pursuant to the NIH ACTIV initiative are posted in a searchable database accessible at There are currently 20 important clinical trials concerning safety and efficacy of the three primary COVID vaccines manufactured by Janssen, Moderna and Pfizer/BioNTech, with the estimated study completion dates one or more years into the future:

Study No.  

Study Title

Estimated Study Completion Date
1 A Study of Ad26.COV2.S for the Prevention of SARS-CoV-2-Mediated COVID-19 in Adult Participants (ENSEMBLE)  

January 2, 2023

2 A Study of Ad26.COV2.S for the Prevention of SARS-CoV-2-mediated COVID-19 in Adults (ENSEMBLE 2) May 31, 2023
3 A Study of Ad26.COV2.S in Adults (COVID-19) February 2, 2024
4 A Study of Ad26.COV2.S in Healthy Pregnant Participants (COVID-19) (HORIZON 1)  

June 20, 2023

5 A Study to Evaluate Efficacy, Safety, and Immunogenicity of mRNA-1273 Vaccine in Adults Aged 18 Years and Older to Prevent COVID-19  

October 27, 2022

6 A Study to Evaluate Safety and Immunogenicity of mRNA-1273 Vaccine to Prevent COVID-19 in Adult Organ Transplant Recipients and in Healthy Adult Participants  

August 26, 2022

7 A Study to Evaluate Safety, Reactogenicity, and Immunogenicity of mRNA-1283 and mRNA-1273 Vaccines in Healthy Adults Between 18 Years and 55 Years of Age to Prevent COVID-19  


April 13, 2022

8 Dose-Confirmation Study to Evaluate the Safety, Reactogenicity, and Immunogenicity of mRNA-1273 COVID-19 Vaccine in Adults Aged 18 Years and Older  

Nov. 1, 2021


9 Study to Describe the Safety, Tolerability, Immunogenicity, and Efficacy of RNA Vaccine Candidates Against COVID-19 in Healthy Individuals  

May 2, 2023

10 A Trial Investigating the Safety and Effects of Four BNT162 Vaccines Against COVID-2019 in Healthy and Immunocompromised Adults  

April 2023

11 Pfizer-BioNTech COVID-19 BNT162b2 Vaccine Effectiveness Study – Kaiser Permanente Southern California July 30, 2023
12 Study to Evaluate Safety, Tolerability & Immunogenicity of BNT162b2 in Immunocompromised Participants ≥2 Years Jan. 24, 2023
13 Study to Evaluate the Safety and Efficacy of a Booster Dose of BNT162b2 in Participants ≥16 Years of Age August 7, 2022
14 Study to Evaluate the Safety, Tolerability, and Immunogenicity of SARS CoV-2 RNA Vaccine Candidate (BNT162b2) Against COVID-19 in Healthy Pregnant Women 18 Years of Age and Older  


July 25, 2022


15 Efficacy and Safety of COVID-19 Vaccine in Cancer Patients Dec. 31, 2022


16 A Trial of the Safety and Immunogenicity of the COVID-19 Vaccine (mRNA-1273) in Participants With Hematologic Malignancies and Various Regimens of Immunosuppression, and in Participants With Solid Tumors on PD1/PDL1 Inhibitor Therapy  


February 25, 2023

17 Post COVID-19 Vaccination Analysis in Healthcare Worker Recipients February 2022
18 The Lymphoma and Leukemia Society COVID-19 Registry February 23, 2031
19 Yale COVID-19 Recovery Study May 3, 2022
20 Host Immune Response to Novel RNA COVID-19 Vaccination January, 2024

As of the date of this document, 173 clinical trials relating to COVID-19 vaccines are underway in the United States alone, as reported at the website.  A true and correct summary of each of these 173 clinical trials, along with the webpage reporting each clinical study, is attached here.

This means that an enormous amount of information regarding long-term effects of the COVID vaccines is not currently known, and will not be known, until completion of a material number of the clinical trials—particularly the targeted trials identified as items no. 1-20, above.