Weizmann institutet (Israel)
https://coronaisrael.org/en/index.html
(Please try to answer them and see how they generate questions based on response.) was
Coronastatus (norway)
Survey from scilifelab (Early versions) https://docs.google.com/forms/d/e/1FAIpQLSewZs5vBPbEoOfvdLvv9UM7K4Qw_xe0hxUMiDIHdhDl0ueRdQ/viewform
COVID symptom tracker
https://apps.apple.com/gb/app/covid-symptom-tracker/id1503529611
(If you go through the app screenshot you get the questions.)
CDC US government (Symptoms)
https://www.cdc.gov/coronavirus/2019-ncov/faq.html#anchor_1584389201096
Outside questionnaire (data application)
https://www.bsg.ox.ac.uk/research/research-projects/oxford-covid-19-government-response-tracker
Comment (from Olli): Please also look for symptoms that differentiates cold/flu from covid19.