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The total number and mass of SARS-CoV-2 virions

Sender, Ron and Bar-On, Yinon M. and Gleizer, Shmuel and Bernsthein, Biana and Flamholz, Avi and Phillips, Rob and Milo, Ron (2021) The total number and mass of SARS-CoV-2 virions. Proceedings of the National Academy of Sciences of the United States of America, 118 (25). Art. No. e2024815118. ISSN 0027-8424. PMCID PMC8237675; PMC7685332. doi:10.1073/pnas.2024815118.

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Quantitatively describing the time course of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection within an infected individual is important for understanding the current global pandemic and possible ways to combat it. Here we integrate the best current knowledge about the typical viral load of SARS-CoV-2 in bodily fluids and host tissues to estimate the total number and mass of SARS-CoV-2 virions in an infected person. We estimate that each infected person carries 109 to 1011 virions during peak infection, with a total mass in the range of 1 μg to 100 μg, which curiously implies that all SARS-CoV-2 virions currently circulating within human hosts have a collective mass of only 0.1 kg to 10 kg. We combine our estimates with the available literature on host immune response and viral mutation rates to demonstrate how antibodies markedly outnumber the spike proteins, and the genetic diversity of virions in an infected host covers all possible single nucleotide substitutions.

Item Type:Article
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URLURL TypeDescription Paper CentralArticle CentralDiscussion Paper
Sender, Ron0000-0002-1165-9818
Bar-On, Yinon M.0000-0001-8477-609X
Gleizer, Shmuel0000-0001-9774-0504
Bernsthein, Biana0000-0002-7957-2575
Flamholz, Avi0000-0002-9278-5479
Phillips, Rob0000-0003-3082-2809
Milo, Ron0000-0003-1641-2299
Alternate Title:The total number and mass of SARS-CoV-2 virions in an infected person
Additional Information:© 2021 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY). Edited by Ken A. Dill, Stony Brook University, Stony Brook, NY, and approved May 10, 2021 (received for review December 13, 2020). We thank Itai Benhar, Gidon Eshel, Shai Fuchs, Thierry Mora, Eran Segal, Maya Shamir, Ziv Shulman, Huicheng Shi, Harinder Singh, Einat Vitner, Aleksandra Walczak, and John Yin for valuable feedback on this manuscript. This research was supported by the European Research Council (Project NOVCARBFIX 646827), Israel Science Foundation (Grant 740/16), Beck-Canadian Center for Alternative Energy Research, Dana and Yossie Hollander, Ullmann Family Foundation, Helmsley Charitable Foundation, Larson Charitable Foundation, Wolfson Family Charitable Trust, Charles Rothschild, Selmo Nussenbaum, Miel de Botton (R.M.), the NIH (1R35 GM118043-01 [Maximizing Investigators' Research Award]) (R.P.), Merkin Institute for Translational Research (R.P.), the Israeli Council for Higher Education via the Weizmann Data Science Research Center, and by a research grant from Madame Olga Klein – Astrachan (R.S.). R.M. is the Charles and Louise Gartner Professional Chair. Y.M.B.-O. is an Azrieli Fellow. Data Availability: All study data are included in the article, SI Appendix, and Dataset S1. R.S. and Y.M.B.-O. contributed equally to this work. Author contributions: R.S., Y.M.B.-O., R.P., and R.M. designed research; R.S., Y.M.B.-O., S.G., B.B., A.F., R.P., and R.M. performed research; R.S., Y.M.B.-O., S.G., B.B., A.F., R.P., and R.M. analyzed data; and R.S., Y.M.B.-O., S.G., B.B., A.F., R.P., and R.M. wrote the paper. The authors declare no competing interest. This article is a PNAS Direct Submission. This article contains supporting information online at
Funding AgencyGrant Number
European Research Council (ERC)646827
Israel Science Foundation740/16
Beck-Canadian Center for Alternative Energy ResearchUNSPECIFIED
Dana and Yossie HollanderUNSPECIFIED
Ullmann Family FoundationUNSPECIFIED
Helmsley Charitable FoundationUNSPECIFIED
Larson Charitable FoundationUNSPECIFIED
Wolfson Family Charitable TrustUNSPECIFIED
Charles RothschildUNSPECIFIED
Selmo NussenbaumUNSPECIFIED
NIH1R35 GM118043-01
Caltech Merkin Institute for Translational ResearchUNSPECIFIED
Council for Higher Education (Israel)UNSPECIFIED
Weizmann Institute of ScienceUNSPECIFIED
Madame Olga KleinUNSPECIFIED
Charles and Louise Gartner Professional ChairUNSPECIFIED
Azrieli FellowshipUNSPECIFIED
Subject Keywords:COVID-19; variants of concern; viral biomass; viral load; genetic diversity
Issue or Number:25
PubMed Central ID:PMC8237675; PMC7685332
Record Number:CaltechAUTHORS:20201118-151353187
Persistent URL:
Official Citation:The total number and mass of SARS-CoV-2 virions. Ron Sender, Yinon M. Bar-On, Shmuel Gleizer, Biana Bernshtein, Avi Flamholz, Rob Phillips, Ron Milo. Proceedings of the National Academy of Sciences Jun 2021, 118 (25) e2024815118; DOI: 10.1073/pnas.2024815118
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:106731
Deposited By: Tony Diaz
Deposited On:18 Nov 2020 23:45
Last Modified:08 Jul 2021 16:48

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