The World Health Organization (WHO) had this Q&A, but is very clear that there is not sufficient evidence to support the idea of “immunity passports” or any form of indication that people are now immune to Covid-19 based on recovering from infection.
Some governments have suggested that the detection of antibodies to the SARS-CoV-2, the virus that causes COVID-19, could serve as the basis for an “immunity passport” or “risk-free certificate” that would enable individuals to travel or to return to work assuming that they are protected against re-infection. There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection.
https://www.who.int/news-room/commentaries/detail/immunity-passports-in-the-context-of-covid-19
WHO YouTube Channel
There is currently insufficient evidence to suggest that this is accurate with regard to this infection – the immune system ‘remembers’ some viruses longer than others, and at present, it is not known exactly what this looks like for the novel coronavirus.
Certainly, as the virus has spread widely, it is to be hoped that immunity proves to last a long time, and that an effective vaccine can be found, given the deadly outcome for a significant number of Covid-19 patients.