COVID-19 Vaccine Position Statement


Johnson & Johnson (J&J) Vaccine Update:

The Janssen COVID-19 Vaccine is now contraindicated for individuals with a history of thrombosis with thrombocytopenia following the Janssen COVID-19 Vaccine or any other adenovirus-vectored COVID-19 vaccines (e.g., AstraZeneca’s COVID-19 vaccine which is not authorized or approved in the United States). Please review the latest Emergency Use Authorization Fact Sheets at

On December 16, 2021, the CDC’s Advisory Committee on Immunization Practices (ACIP) voted to recommend that mRNA COVID-19 vaccines be preferred over the Janssen COVID-19 Vaccine for the prevention of COVID-19 for all people 18 years of age and older. The CDC has endorsed the recommendation. More information can be found on the CDC webpage.

The Janssen COVID19 Vaccine has not been approved or licensed by the U.S. Food and Drug Administration (FDA), but has been authorized by FDA through an Emergency Use Authorization (EUA) for active immunization to prevent Coronavirus Disease 2019 (COVID19) in individuals 18 years of age and older. The emergency use of this product is authorized only for the duration of the declaration that circumstances exist justifying the authorization of the emergency use of the medical product under Section 564(b)(1) of the FD&C Act, unless the declaration is terminated or authorization revoked sooner.

NATF COVID-19 Vaccine Position Statement

The North American Thrombosis Forum (NATF) strongly recommends that all eligible individuals get vaccinated against COVID-19, including:

  • People who have had a blood clot in the past
  • People with genetic clotting disorders (such as factor V Leiden) or who have a family history of blood clots 
  • People who take anticoagulation (sometimes called blood thinners)
  • People who take antiplatelet medications (aspirin, clopidogrel, ticagrelor)
  • People who have bleeding disorders such as hemophilias

Vaccination is the key to protecting our individual health and limiting the spread of COVID-19 in our communities. It’s also the best tool we have to prevent blood clots and other vascular complications associated with COVID-19, such as pulmonary embolism (PE), deep vein thrombosis (DVT), and stroke, as well as the chronic symptoms, called “COVID long-haulers syndrome,” which can persist indefinitely and be debilitating. 

What We Know:

  • Infectious diseases spread quickly within communities that have high numbers of unvaccinated people. As more people become vaccinated, disease transmission from person to person declines, which is known as herd immunity. When we achieve herd immunity, we protect the most vulnerable people in our society, including the elderly and those who have weakened immune systems.
  • The available COVID-19 vaccines are safe and effective. The U.S. Food and Drug Administration (FDA) has stringent standards that vaccine developers must meet. All vaccines that are distributed in the U.S. are rigorously tested in large clinical trials and continue to be monitored. [Individuals are encouraged to contact their healthcare provider if they have questions or concerns about any of the available vaccines.]
  • There is a proven link that being infected with COVID-19 increases the risk of having a blood clot, and COVID-19 vaccination dramatically reduces the risk of COVID-19-associated blood clots. Current data show that the benefits of COVID-19 vaccination far outweigh the risks.
  • Even though more people are getting vaccinated, we must continue to wear masks in public, socially distance, and frequently wash our hands. 
  • Future research on COVID-19 vaccines should focus on:
    • COVID-19 variants, including the UK, South African, and Brazilian variants
    • The duration of protection 
    • Optimal timing of booster shots
    • Global health initiatives to support universal COVID-19 vaccination 

Disclaimer: This position statement reflects the consensus of the NATF Board of Directors and Medical Advisory Board and is based on the best available evidence. It is provided for informational purposes only and is not intended to serve as personalized medical advice. If you have specific questions or concerns about the vaccine, please consult your personal physician or healthcare provider.

NATF does not endorse or recommend one vaccine over another, nor do we endorse any one vaccine manufacturer and/or the products they distribute.  

NATF Executive Board

Samuel Z. Goldhaber, MD Associate Chief and Clinical Director, Cardiovascular Division, Brigham and Women’s Hospital (BWH)

John Fanikos, RPh, MBA Director of Pharmacy Business and Financial Services, Brigham and Women’s Hospital (BWH)

Jawed Fareed, PhD Director of the Hemostasis and Thrombosis Research Laboratories, Loyola University Medical Center

Gregory Piazza, MD, MS Section Head of Vascular Medicine and Staff Physician, Cardiovascular Division, Brigham and Women’s Hospital (BWH)

Christian T. Ruff, MD, MPH Director of General Cardiology, Cardiovascular Division, Brigham and Women’s Hospital (BWH)

Jeanine M. Walenga, PhD Co-Director of the Hemostasis and Thrombosis Research Laboratories, Loyola University Medical Center

NATF Medical Advisory Board

Brenda Shisslak Patient Representative

Alex Spyropoulos, MD System Director of Anticoagulation and Clinical Thrombosis Services, Northwell Health System

Aaron Aday, MD, MS Investigator, Vanderbilt Translational and Clinical Cardiovascular Research Center, Vanderbilt University Medical Center

Margaret Fang, MD, MPH Hospitalist, Research Director at the Division of Hospital Medicine, and Medical Director of the Anticoagulation Clinic, University of California San Francisco (UCSF)

Tzu-Fei Wang, MD, MPH Associate Professor of Medicine, Division of Hematology, University of Ottawa Ottawa, Canada

Jennifer Ballard-Hernandez, DNP Cardiology Nurse Practitioner, Tibor Rubin VA Medical Center and Cardiology Clinical Nurse Advisor to the Office of Nursing Services for VA Central Office

Tara Lech, PharmD Anticoagulation and Cardiovascular Clinical Pharmacy Specialist, Beth Israel Lahey Health


The United States Food and Drug Administration. FDA authorizes booster dose of Pfizer-BioNTech COVID-19 vaccine for certain populations. Updated September 22, 2021. Accessed September 30, 2021.

The United States Food and Drug Administration. FDA approves first COVID vaccine. Updated August 23, 2021. Accessed August 24, 2021.

Young K. CDC, FDA to Resume J&J COVID-19 Vaccination Following Pause Over Rare Clots. NEJM Journal Watch. Updated April 24, 2021. Accessed April 25, 2021.

The Centers for Disease Control and Prevention; The Food and Drug Administration. Joint CDC and FDA statement on Johnson & Johnson COVID-19 vaccine. Updated April 13, 2021. Accessed April 13, 2021.

The Centers for Disease Control and Prevention. Data and statistics on venous thromboembolism. Updated February 2020. Accessed March 2021.

Previous Updates

Pfizer-BioNTech COVID-19 Vaccine Updates:

September 2021

On September 22, 2021, the U.S. Food and Drug Administration amended the emergency use authorization (EUA) for the Pfizer-BioNTech COVID-19 vaccine. This amendment allows for the use of a single booster dose to be administered at least six months after receiving the second primary vaccine shot and applies to the following groups:

  • Individuals 65 years of age and older;
  • Individuals 18-64 years of age at high risk of severe COVID-19; and 
  • individuals 18-64 years of age whose frequent institutional or occupational exposure to SARS-CoV-2 puts them at high risk of serious complications of COVID-19, including severe COVID-19.

This booster authorization applies only to the Pfizer-BioNTech COVID-19 vaccine. 

August 2021

On August 23, 2021, the U.S. Food and Drug Administration fully approved the the Pfizer-BioNTech COVID-19 vaccine for the prevention of COVID-19 disease in individuals ages 16 and older. The vaccine also continues to be available under EUA, including for individuals 12-15 years of age and for the administration of a third dose in certain immunocompromised individuals.

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