2/7 Looking at numbers, we observe that on May 4th, we have roughly the same number of active cases than March 16th, BUT with 6 times patients in hospitals than the first day of the #lockdown. However, Re decreased by more than a factor 4 ! 
3/7 Re/R0 is roughly the product of three parameters : Re = T.C.tau where T is the transmissibility of the virus at each contact, C is the average number of contacts per unit of time, and tau is the duration of the disease.
4/7 One understands that we can control two factors T and C. Confinement decreased mostly our average contact number C by social distancing. As a result, Re decreased by more than a factor 4 !
5/7 After May 4, factor C will increase again ! Hopefully, wearing a face mask decreases T. By chance, Re could be unchanged if we take a lot of precautions. But this is an optimistic perspective... [how to fabricate a mask ]
6/7 A realistic scenario would correspond to successive small jumps of Re after May 4, 11, 18, 25 (different phases of the exit strategy). By assuming that Re is on average 0.8 (from @sciensano), let us have a look at the SEIR model.
7/7 Three scenarios. Increasing Re only by 20%, 30%, 40% at each phase of the exit strategy. Conclusion : ICU saturation in August, July and June respectively. A second wave/confinement is therefore unavoidable. We need to follow the data in the next weeks...
