The World Health Organization (WHO) has warned that there is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection.
In a scientific brief issued on April 24, WHO said there was no proof that one-time infection could lead to immunity.
“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,” said the WHO statement, adding: “There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection.”
The new guidance comes amid media reports that some countries have announced their intention to issue so-called “immunity cards” that would allow individual travel, based on the assumption that a person infected with the coronavirus could not be infected a second time.
While most of the relevant studies show that people who have recovered from infection have antibodies to the virus, WHO noted that as of yesterday, “no study has evaluated whether the presence of antibodies to SARS-CoV-2 confers immunity to subsequent infection by this virus in humans.”
“At this point in the pandemic, there is not enough evidence about the effectiveness of antibody-mediated immunity to guarantee the accuracy of an ‘immunity passport’ or ‘risk-free certificate,’” the WHO warned.
WHO said: “People who assume that they are immune to a second infection because they have received a positive test result may ignore public health advice. The use of such certificates may therefore increase the risks of continued transmission.”
The agency later clarified in a tweet that it expects that most people who are infected with COVID-19 will develop an antibody response that will provide some level of protection. “What we don’t yet know is the level of protection or how long it will last. We are working with scientists around the world to better understand the body’s response to COVID-19 infection.”