If the US CDC and the German health minister have yet to certify an antibody test for SARS-CoV-2, how can a study not only detect them, but also quantify them over time accurately?
All coronaviruses historically (not to mention respiratory viruses in general) create an immunity that is measured in years, not months or weeks.
Also if a patient is not immune then who is questioning the accuracy of whether they had this in the first place?

Seems like a scare piece to keep people inside or push a political agenda.
Simply saying that immunity lasts a short time is akin to saying I will drop a ball and it will go up, not fall to the ground. The burden of proof is on the exception, not the rule. Simply throwing the idea out there seems to have a political or "scare" motive.

Also, people in power including many scientists were ALL underprepared for this. They are all embarrassed. It is human nature when you make a mistake to characterize the problem as something bigger or completely different to save face.

OVERREACTION (and rewriting science is that) is not a solution for being UNDERPREPARED