We thank V. Pelechano, X. Yin, and V. Lohmann for helpful discussions and sharing unpublished work. We thank U. Merle for providing specimens and the diagnostic laboratory team at Heidelberg University Hospital for providing RNA samples isolated from pharyngeal swabs collected from patients being tested for COVID-19. We thank V. Sonntag-Buck, A.-M. Heuser, I. Ambiel, S. Winter, T. Müller, and S. Horner for excellent technical support. We thank A. Uvarovskii and S. Ovchinnikova for IT-related help and S. Kreger and U. Jäkle for additional technical help. Funding: V.L.D.T., A.F., and P.C. were supported by the Chica and Heinz Schaller foundation. M.K. was supported by the Deutsche Forschungsgemeinschaft (DFG; grant no. KN498/11-1). S.B. was supported by the Heisenberg program of the DFG. Author contributions: V.L.D.T., H.-G.K., M.K., and S.A. conceived and planned the study. V.L.D.T., M.M., K.B., and M.K. planned and designed the experiments on the RT-LAMP assay and performed them together with Daniel Kirrmaier, A.F., S.K., and P.C. V.L.D.T., K.B., and M.K. performed the experiments for the swab–to–RT-LAMP assay. K.H. designed the LAMP-sequencing assay and performed it with Daniel Kirrmaier and M.K. K.B. performed the RT-qPCR analyses of samples and organized, together with I.B.M., P.S., Dina Khalid, and H.-G.K., provision of the samples by the diagnostic laboratory. D.P. and C.G. tested sample handling and logistics strategies. V.L.D.T., M.K., M.L.S., and S.B. tested viral inactivation protocols. S.A. performed data analysis of the RT-LAMP experiments, together with L.P.M.K. and K.H. K.H. analyzed the LAMP-sequencing data. V.L.D.T. analyzed the swab–to–RT-LAMP data. V.L.D.T., K.H., P.C., L.P.M.K., M.K., and S.A. analyzed and interpreted the data. V.L.D.T., K.H., M.K., and S.A. wrote the manuscript, with input from all authors. Competing interests: P.S. has consulted for Janssen. The other authors declare that they have no competing interests. Data and materials availability: All data associated with this study are in the main text or the Supplementary Materials. The R code used to perform analyses and produce figures can be found on GitHub, together with all raw data tables: https://github.com/anders-biostat/LAMP-Paper-Figures. This work is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. This license does not apply to figures/photos/artwork or other content included in the article that is credited to a third party; obtain authorization from the rights holder before using this material.