14) Now, what does this all mean? A) With this assay we can figure out who was infected and who wasn't. That means we can determine the true infection rate and infection fatality rate. B) We can use the assay to screen for people who seroconverted and are now immune.....

15)...and they can donate their serum and it can maybe used to treat patients. C) We can test health care workers and ask the ones who are already immune to work with infectious patients. In that way the virus is not easily spread to colleagues or other patients. And D) ....

16)...we can now use this assay to better study how our immune response reacts to the virus. And then there are two more take home messages that are important: First, it looks like we are all naive, meaning we have no immunity whatsoever to SARS-CoV-2. That would....

17)....explain why it spreads so quickly. And second, it means we make an immune response to the spike. Antibodies to the RBD domain are often neutralizing, and it is likely (but needs to be confirmed) that once the antibody response sets in, we become protected.

18) Please keep in mind that these conclusions are preliminary and based on small numbers. Larger studies to confirm this are needed and ongoing. We have started to share the reagents globally and hope that this or similar assays can be set up in many places.

19) Finally, I want to thank the student who took the lead on this, Fatima Amanat as well as my whole group of dedicated students, postdocs, techs and assistant professors who dropped all their beloved influenza work to help out with creating tools to fight SARS-CoV-2.