The World Health Organization (WHO) warned on Saturday that there is no evidence that people who have been diagnosed with the new coronavirus have been vaccinated and protected from infection again.
The warning indicates that the issuance of immune passports may encourage the continued spread of the epidemic.

There is currently, no evidence that people who have recovered from # COVID19 have antibodies protected from a second infection the WHO said in a statement.
As of April 24, 2020, no study had assessed whether the presence of SARS-CoV-2 antibodies conferring immunity to post-infection with this virus in humans.
Some governments, who want to gradually return to work and resume economic activity, have come up with the idea of issuing documents that support people's immunity on the basis of serological tests that reveal the presence of antibodies in the blood.
But the World Health Organization warns that the effectiveness of immunization thanks to antibodies has not yet been determined, and the available scientific data do not justify the granting of an immunization passport or no risk certificate.

At this the point in the epidemic there is insufficient evidence of the effectiveness of antibody-mediated immunity to ensure the accuracy of an immunity passport or risk-free certificate.
Those who are presumed immune to a second infection because they have received a positive the test result may ignore public health advice the WHO said.

Therefore the use of such certificates could increase the risk of continuous transmission.
The World Health Organization also believes that the serological tests currently used need additional verification to determine their accuracy and reliability.

In particular, tests should make it possible to distinguish between the immune the response of the new coronavirus and the antibodies produced during infection with another virus from six known human coronaviruses four of which are spread and cause mild colds.
The other two are responsible for the Middle East respiratory syndrome and severe acute respiratory syndrome.

People infected with one or another of these viruses is able to produce antibodies that interact with the produced antibodies in response to the infection caused by SARS-CoV-2
The WHO said, stressing the importance of being able to identify them.