Note: To send this letter to your Governor, please text Masks4All to 50409.

If you’re a medical or scientific expert with relevant background and would like to sign this letter, you can sign the letter here.

We have an urgent message about some critical new scientific research. It strongly suggests that requiring fabric mask use in public places could be amongst the most powerful tools to stop the community spread of COVID-19.

An international cross-disciplinary review of the scientific research by 19 experts and other recent research shows that:

• People are most infectious in the initial period of infection, when it is common to have few or no symptoms
• Cloth masks obstruct a high portion of the droplets from the mouth and nose that spread the virus
• Non-medical masks have been effective in reducing transmission of coronavirus
• Cloth masks can be washed in soapy water and re-used
• Places and time periods where mask usage is required or widespread have been shown to substantially lower community transmission
• Public mask wearing is most effective at stopping spread of the virus when the vast majority of the public uses masks
• Laws appear to be highly effective at increasing compliance and slowing or stopping the spread of COVID-19.

The preponderance of evidence, in both laboratory and clinical settings, indicates that mask wearing reduces the transmissibility per contact by reducing transmission of infected droplets. The decreased transmissibility could substantially reduce the death toll, other harms to public health, job losses and economic losses. The cost of such masks is very low by comparison.

Modeling suggests that widespread public mask use, in conjunction with other measures, could bring the effective reproduction number (R) beneath 1.0, thus halting the growth of the pandemic.

Therefore, we ask that government officials require cloth masks to be worn in all public places, such as stores, transportation systems, and public buildings as soon as possible. This action will prevent people who are infectious from unknowingly spreading the disease.

We also ask business leaders who offer products and services to the public to require their employees and customers to wear masks whether or not it is required by local law. This vital step will help protect workers and customers.

Such requirements will greatly increase the rate of mask wearing. This should be done in conjunction with, not as a replacement for, hand hygiene, physical distancing, testing, and contact tracing strategies.

This requirement should be introduced alongside clear guidelines for the production, use and sanitization or re-use of face masks. We urge you to also consider their distribution as shortages allow.

There is no need to wait for availability of medical-grade masks; any face covering, including a piece of cloth, a scarf, bandana, t-shirt, or paper towel, appears to be effective.

Sincerely,

Organizing Signatories

Note: institutional affiliation is provided for identification purposes only and does not indicate or imply an endorsement of the views expressed in this letter by any institution.

Jeremy Howard: Distinguished research scientist, University of San Francisco, co-founder fast.ai, member World Economic Forum Global AI Council

Dr Vincent Rajkumar: Editor in Chief, Blood Cancer Journal

North American Signatories

Dr Harold Varmus: Nobel Prize-winning virologist; Professor, Weill Cornell Medicine; former Director, NIH and NCI

Dr Bengt Holmström: Nobel Prize-winning economist; Professor, Economics, MIT

Dr Siddhartha Mukherjee: Professor of Medicine, Columbia University Medical Center; Time 100 most influential people; Best-selling author

Dr Eric Topol: Director, Scripps Research Translational Institute; Executive VP & Professor, Molecular Medicine, Scripps Research; Best-selling author

Dr Robert Wachter: Professor, Medicine Chair, UCSF;  Chair of Advisory Board, Healthcare Improvement Studies, Univ of Cambridge; Best-selling author

Dr Anne W. Rimoin: Professor, Department of Epidemiology; Director, UCLA Center for Global and Immigrant Health; Director, UCLA-DRC Health Research and Training Program

Dr Erik Brynjolfsson: Professor, MIT Sloan; Senior Fellow, Stanford Institute for Human-Centered AI & Stanford Institute for Economic Policy Research; Bestselling author.

Dr Diana Romero: Chief Editor, Nature Reviews Clinical Oncology

Dr Sagar Lonial: Chair and Professor, Department of Hematology and Medical Oncology; Anne and Bernard Gray Family Chair in Cancer; Chief Medical Officer, Winship Cancer Institute, Emory University School of Medicine.

Dr Albert Icksang Ko: Professor, Epidemiology and Medicine, Chair, Epidemiology of Microbial Diseases, Yale School of Public Health

Dr Christina Ramirez: Professor of Biostatistics, UCLA Fielding School of Public Health

Dr Carlo Brugnara: Editor in Chief, American Journal of Hematology

Dr Michael Picard: Editor in Chief, Journal of the American Society of Echocardiography

Dr Jeff Drazen: Professor of Medicine, Harvard

Dr Monica Bertagnolli: Chair, Board of Directors, American Society of Clinical Oncology; Group Chair, Alliance for Clinical Trials in Oncology

Dr Yann Le Cun: Professor of Computer Science and Data Science, NYU; Chief AI Scientist, Facebook; Turing Laureate 2019

Dr Edith Mitchell: Past President, National Medical Association; Professor, Thomas Jefferson University

Dr Corey Cutler: Medical Director, Stem Cell Transplantation, Harvard Medical School

Dr De Kai: Professor, Computer Science and Engineering, Hong Kong University of Science and Technology; Distinguished Research Scholar, Berkeley; Founding Fellow, Association for Computational Linguistics

Dr Charles Ericsson: Professor and Head of Infectious Diseases, McGovern Medical School, University of Texas

Dr Ann Prestipin: Senior Vice President, COVID response, Massachusetts General Hospital

Dr Noopur Raje: Professor, Harvard Medical School; Director Center for Multiple Myeloma, Chair in Oncology, Massachusetts General Hospital Cancer Center

Dr Christopher Manning: Professor of Linguistics and Computer Science, Stanford

Dr Ruvandhi Nathavitharana: Vice Chair, TB Proof; Associate Professor, Division of Infectious Diseases Beth Israel Deaconess Medical Center Harvard Medical School

Dr Edward Nardell: Professor, Harvard Medical School

Dr Gregg Gonsalves: Assistant Professor, Epidemiology, Yale; Co-Director, Global Health Justice Partnership; Co-Director, Collaboration for Research Integrity and Transparency

Dr David McAdams: Professor, Business Administration (Fuqua School of Business) and Economics, Duke University

Dr. Walt de Heer, Regent’s Professor of Physics, Georgia Institute of Technology

Dr Lin Chen: Associate Professor, Harvard Medical School;, Director of Travel Medicine Center, Mount Auburn Hospital

Dr Marc Suchard: Professor of Human Genetics, Biostatistics and Biomathematics, UCLA David Geffen School of Medicine

Marietje Schaake: International Director of Policy, Cyber Policy Center, Stanford; Member of the European Parliament (MEP) 2009-2019

Dr Michael Joyner: Anesthesiologist and Lead Investigator, Convalescent Plasma Program for COVID

Dr Jagmeet Singh: Professor, Harvard Medical School

Dr James Armitage: Professor of Medicine, University of Nebraska Medical Center

Dr Eric Westman: Professor, Duke University Medical Center, Past President, Obesity Medicine Association

Dr Chadi Nabhan: Professor, Department of Clinical Pharmacy and Outcomes Sciences, University of South Carolina; Chairman, Caris Precision Oncology Alliance

Dr Ik-Kyung Jang: Professor of Medicine, Harvard

Dr Anas Younes: Professor of Medicine, Memorial Sloan Kettering Cancer Center

Dr James Januzzi: Professor of Medicine, Harvard; Professor, Cardiology, Massachusetts General Hospital

Dr Vikas Sukhatme: Dean, Emory School of Medicine; Chief Academic Officer, Emory Healthcare

Dr Barbara Murray: Past President, Infectious Diseases Society of America; Professor of Medicine, University of Texas

Dr Michael Lin: Associate Professor, Neurobiology and Bioengineering, Stanford; Member of Scientists to Stop Covid-19

Dr Priya Sampathkumar Infection Control and Infectious Disease Specialist

Dr Mike Thompson: Director, Early Phase Cancer Research, Aurora Health Care

Dr David Shlim: Past President, International Society of Travel Medicine; Medical Director, Jackson Hole Travel and Tropical Medicine

Dr Daniel Morgan: Professor of Epidemiology and Public Health and Medicine, University of Maryland

Dr Lee Ellis: Professor of Surgery, Molecular and Cellular Oncology

Dr Dawd Siraj: Professor, Infectious Diseases, University of Wisconsin Madison

Dr Michael Sauri: Clinical Professor, Occupational Medicine, Johns Hopkins and USUHS Bethesda

Dr Amy Tan: Associate Professor, Medicine, University of Calgary

Dr Ross Levine: Professor, Economic Analysis and Policy, UC Berkeley

Dr Netanya Utay: Assistant Professor, Medicine, University of Texas

Dr Avinash Sinha: Assistant Professor, Anesthesia, McGill University

Dr Chip Lavie: Editor in Chief, Progress Cardiovascular Diseases; Professor and Medical Director, John Ochsner Heart and Vascular Institute

Dr Lin Chen: Associate Professor, Medicine, Harvard

Dr Katrina Armstrong: Physician in Chief, Massachusetts General Hospital

Dr Carlos del Rio: Professor of Medicine, Global Health & Epidemiology, Emory University

Dr Jordan Lake: Associate Professor, Infectious Diseases, University of Texas

Anna Kaltenboeck: Program Director, Center for Health Policy and Outcomes, Memorial Sloan Kettering Cancer Center

Dr Krishna Komanduri: Chief, Division of Transplantation and Cellular Therapy; Professor of Medicine, Microbiology and Immunology, University of Miami

Dr Mark Harrington: Executive Director, Treatment Action Group

Dr Vishal Sikka: CEO, Vianai Systems. Board of Directors, Oracle and BMW; Former CEO, Infosys

Dr Joe Vipond: Clinical Assistant Professor, Emergency Medicine, University of Calgary

Dr Jason Abaluck: Associate Professor of Economics, Yale School of Management 

Dr Miguel Perales: Chief, Adult Bone Marrow Transplantation Service, Memorial Sloan Kettering Cancer Center

Dr Judith Chevalier: Professor, Economics and Finance, Yale University

Dr Lawrence Greenblatt: Professor, Department of Community and Family Medicine, Duke University

Dr Adriaan Bax: Member, National Academy of Sciences

Dr Zeynep Tufekci: Associate Professor, Information and Library Science, UNC; Adjunct Professor, Department of Sociology; Writer: The Atlantic and NY Times

European Signatories

Dr Richard Horton: Editor in Chief, The Lancet; Honorary Professor, London School of Hygiene & Tropical Medicine, University College London, and University of Oslo.

Dr Magdalena Skipper: Editor in Chief, Nature

Dr Martin McKee CBE: Past President, European Public Health Association; Professor, Public Health, London School of Hygiene & Tropical Medicine; Director, European Observatory

Dr Trish Greenhalgh OBE: Professor, co-Director of Interdisciplinary Research In Health Sciences, Primary Health Care Sciences, University of Oxford

Dr Meletios-Athanasios Dimopoulos: Rector, National and Kapodistrian University of Athens

Dr Jesus San-Miguel: Director, Clinical & Translational Medicine, Universidad de Navarra

Dr Vladimir Zdimal: Head of Department of Aerosols Chemistry and Physics; Institute of Chemical Process Fundamentals of the Czech Academy of Science

Dr Charles Tannock MBE: Member of the European Parliament (MEP) 1999-2019; NHS Consultant

Dr Keertan Dheda: Professor, Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine; Director, Centre for Lung Infection and Immunity; Head: Division of Pulmonology, University of Cape Town; Professor of Medicine, Groote Schuur Hospital.

Dr KK Cheng, Director, Institute of Applied Health Research, University of Birmingham

Dr Mario Boccadoro: Director, Hematology, University of Torino

Dr Adrian Alegre: Head Hematology Department, Universitary Hospital La Princesa

Dr David Wraith: Director, Institute of Immunology and Immunotherapy, University of Birmingham

Dr Anna Sureda: Head, Clinical Hematology Department, Catalan Institute of Oncology; President, Spanish Group for stem Cell Transplantation and Cellular therapy

Dr Miguel Sanz: Researcher Emeritus, Instituto de Investigación Sanitaria La Fe; Honorary Professor, Medicine, University of Valencia

Dr Carlos Solano: Professor of Medicine, University of Valencia; Director, HSCT and Immune Therapy program, Hospital Clinico Universitario

Dr Jürgen Kuball: Chair, Department of Hematology, UMC Utrecht

Dr Catherine Cordonnier: Professor and Head of Haematology, Henri Mondor University Hospital

Dr Javier Zulueta: Director, Pulmonary Medicine, Clinica Universidad de Navarra

Dr Anna Rotkirch: Research Professor, Population Research Institute, Family Federation of Finland

Dr Key Pousttchi: Professor and past chair, Business Informatics and Digitalization, University of Potsdam

Dr Chris Papadopoulos: Public Health Director, University of Bedfordshire

Dr Alexey Morgunov: CEO, Manifold Research; Lecturer, University of Cambridge

Dr Christophe Rapp: President, French Society of Travel Medicine

Dr Helene-Mari van der Westhuizen: Oxford University; Co-founder TB Proof

Dr Frederik Questier, Professor, Vrije Universiteit Brussel

Dr Lucica Ditiu: Executive Director, Stop TB Partnership

African Signatories

Dr Anneke Hesseling, Professor, Dept Pediatrics and Child Health, Stellenbosch University; Director of the Desmond Tutu TB Centre

Dr Rodney Ehrlich: Emeritus Professor, Senior Research Scholar, School of Public Health and Family Medicine, University of Cape Town

Dr Shaheen Mehtar, (retired) Professor, University of Stellenbosch, Chair of Infection Control Africa Network (ICAN)

Dr Angela Dramowski: Professor, Pediatric Infectious Diseases, Department of Pediatrics and Child Health, Stellenbosch University

Dr Gavin Churchyard: CEO, The Aurum Institute; Honorary Professor, University of Witwatersrand; Honorary Professor, London School of Hygiene and Tropical medicine

Dr Arne von Delft: University of Cape Town; Co-founder of TB Proof

South American Signatories

Dr Guillermo Ruiz-Arguelles: Director General, Centro de Hematologia y Medicina Interna de Puebla

Dr Luis Lamb: Professor, Computer Science and AI, Federal University of Rio Grande do Sul; Secretary of State for Innovation, Science and Technology

Asian Signatories

Dr Lalit Kumar: Professor and Head of Medical Oncology, All India Institute of Medical Sciences

Dr Lei-Han Tang, Professor, Director, Institute of Computational and Theoretical Studies, Hong Kong Baptist University

Dr Chi Chiu Leung: Editor-in-Chief, International Journal of Tuberculosis and Lung Disease; Chairman, Advisory Committee on Communicable Diseases, Hong Kong Medical Association

Dr Mammen Chandy: Director, Tata Medical Center

Dr Tai Hing Lam: Chair Professor, Community Medicine, Professor in Public Health, University of Hong Kong

Dr Mushfiq Mobarak: Scientific Director, Innovations for Poverty Action, Bangladesh;  Professor of Economics, Yale

Dr Zhiyuan Li: Professor, Center for Quantitative Biology, Peking University

Dr Hisao Hayakawa: Professor, Theoretical Physics, Kyoto University

Oceania Signatories

Dr James Brown: Professor of Statistics, University of Technology Sydney

Dr Ben Marais: Associate Professor Paediatrics & Child Health, University of Sydney

Dr Bart Willems: Co-founder, TB Proof; Public Health Medicine Specialist, Nga Tai Ora, Public Health Northland

Additional Signatories (after initial release)

Dr Michaela Routhu: Assistant Professor

Dr John Middleton: President, Association of Schools of Public Health in the European Region

Dr Steve A. N. Goldstein: Vice Chancellor, Health Affairs, Distinguished Professor of Pediatrics, Physiology & Biophysics, University of California, Irvine

Dr Alan Barbour: Distinguished Professor of Medicine and Microbiology & Molecular Genetics, University of California Irvine

Dr Panu Poutvaara: Professor of Economics at the University of Munich and Director of the ifo Center for International Institutional Comparisons and Migration Research

Dr Gary Slutkin: Former Chief, Intervention Development, World Health Organization; former Director, East and Central African Programmes, Global Program on AIDS, WHO

Dr Melanie Thompson: Principal Investigator, AIDS Research Consortium of Atlanta

Dr David Fisman: Professor, Dalla Lana School of Public Health, University of Toronto

Dr Irfan Dhalla: Vice-President, Unity Health Toronto; Associate Professor, University of Toronto

Dr Laura Davisson: Associate Professor Of Medicine West Virginia University, Governor of WV Chapter of the American College of Physicians

Dr Bart Croes: Member of the Board of Atmospheric Sciences and Climate at NASEM. Chief of the Research Division (retired) at the California Air Resources Board

Dr Rama Ramakrishnan: Professor of the Practice of Data Science, MIT

Dr Michael LaGier: Associate Professor of Biology and Department Chair

Dr Linsey Marr: Charles P. Lunsford Professor of Civil and Environmental Engineering

Dr Guruswamy Kumaraswamy: Professor of Chemical Engineering, IIT Bombay

Dr Sherri Alderman: Adjunct Faculty Portland State University, American Academy of Pediatrics Council on Early Childhood Executive Committee

Dr Andrew Noymer: Associate Professor, Public Health, University of California, Irvine

Dr Shirley Ho: Group Leader of Cosmology X Data Science

Dr Randall King: Professor of Cell Biology, Harvard Medical School

Dr Giovanni Battista Migliori: Chair, Global Tuberculosis Network

Dr Eric Feigl-Ding: Senior Fellow, Chief Epidemiologist, Federation of American Scientists. Chief Health Economist, Director of Epidemiology, Microclinic International

Dr Yogi Goswami: Distinguished University Professor and Director, Clean Energy Research Center, University of South Florida

Dr Krishanu Saha: Associate Professor, Department of Biomedical Engineering, University of Wisconsin-Madison

Dr Alan Tan: Director of GU medical oncology

Dr John Middleton: President, Association of Schools of Public Health in the European Region

Dr Elson Romeu Farias: Professor de Medicina da Universidade Luterana do Br

Dr Prabhjot Singh: Associate Professor of Medicine and Global Health, author Dying and Living in the Neighborhood: A Street Level View of America’s Healthcare Promise

Dr Carlos Ramos: Professor of Medicine, Center for Cell and Gene Therapy, Baylor College of Medicine

Dr Allyson Ocean: Associate Professor of Clinical Medicine, Weill Cornell Medical College; Co-founder and Chair of Scientific Advisory Board of Let’s Win! Pancreatic Cancer.

Dr Joshua Gans: Author of Economics in the Age of COVID-19

Dr Artur Jurczyszyn: Professor at the Jagiellonian University, President the Myeloma Tretment Foundation in Poland

Dr Ranu Dhillon: Former Special Advisor to the President of Guinea on Ebola; Division of Global Health Equity, Brigham & Women’s Hospital/Harvard Medical School

Dr Nicholas Gruen: CEO, Lateral Economics