A French Study on Undetected Cases

From France, yet more evidence of how many asymptomatic cases there may be.  (Medrxiv Paper)   Officials conducted a study of students, siblings, parents and staff at a high school in a town.  They tested the group for antibodies.  In addition, they examined blood donations at blood banks for the presence of those antibodies.  661 were tested and 171 had antibodies, or 26%.  In students, the infection rate was 41% and 11% in parents and siblings.  The rate of antibodies in blood bank samples was 3%.  No one died.   68% of participants reported respiratory symptoms (not necessarily from the virus) from January 13 to one week before the blood sampling.  Major symptoms were reported by 49% and minor symptoms by 20%.  The rate of people with no symptoms was 32%, but almost all those who had symptoms had a mild illness.  Ten people said they went to the hospital, nine tested positive, for a hospitalization rate of 5.3% among the infected.  Among the people who tested positive, 71% said they had a major symptom, 12% a mild one and 17% none.  The students and staff had a higher rate of infection than did parents and siblings.  Now here is something interesting, smokers had a much lower rate of infection.  Since participation was voluntary, and those who though they have been sick may have been more likely to participate, extrapolation may be limited.  But once again we see that large numbers of people may have been infected and more critically, almost all had non-serious illnesses.  So all those scary modeling parameters need to be adjusted appropriately.