There is no evidence that people who have recovered from COVID-19 are protected from a second infection, the World Health Organization warned Saturday as the worldwide death toll topped 200,000, NBC News reports.
The WHO tweeted that it was continuing to review the evidence on antibody responses to COVID-19, adding that most studies suggest that people who have recovered from the infection have antibodies to fight the virus.
"However, some of these people have very low levels of antibodies in their blood," it said.
It also advised against the use of so-called immunity passports, which have been suggested in some countries as a way to allow people to travel or return to work on the assumption that they are immune to the coronavirus that causes COVID-19.
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