The World Health Organisation said there is currently "no evidence" that people who have recovered from COVID-19 and have antibodies for the virus are protected from a second coronavirus infection.
In a scientific brief, the United Nations agency warned governments against issuing "immunity passports" or "risk-free certificates" to people who have been infected as their accuracy cannot be guaranteed.
The WHO said the practice could actually increase the risks of continued spread, as people who have recovered may ignore advice about taking standard precautions against the virus.
The health agency said: "Some governments have suggested that the detection of antibodies to the SARS-CoV-2, the virus that causes COVID-19, could serve as the