The World Health Organization (WHO) said on Saturday that there was currently "no evidence" that people who have recovered from COVID-19 and have antibodies 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 could not be guaranteed.

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, it 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 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," the WHO said.

"There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection," it said.