Trust me,
people with Covid-19 will lie

https://medicalxpress.com/news/2020-08-people-covid-symptoms-distancing.html

Sample quote

Participating in the research were 451 adults ages 20 to 82 years living in the U.S. Most identified as having a post-secondary education.
...snip...34 percent of COVID-19 positive participants had denied having symptoms when asked by others; 55 percent reported some level of concealment of their symptoms

End quote