Depends on the virus load you contract, if the density of exposure increases, more and more people will need hospitalisation, when that need overwhelms the medical facilities available more and more people will be dying in public and spreading the disease in public in larger amounts, leading to a much more deadly second wave, while current evidence seems to show having had the disease only provides immunity for a couple of weeks and will leave to open to relapse and a possibly much more severe second bout.

@LenHazell53 Thankmyou for the info. I was not aware that immunity could be temparary. Do you have a link?