There is "no evidence" that people cannot catch coronavirus twice, the World Health Organisation (WHO) have warned. It has cautioned against the idea of “immunity passports” amid the coronavirus pandemic and says there is a lack of evidence that those who have recovered from Covid-19 and have antibodies are protected against a second infection.The concept of “immunity passports” and “risk free certificates” has been raised as a way of allowing people to return to work.However, the Geneva-based UN health agency have now said in a scientific brief, published today, that more research is needed before such an idea can be supported.The WHO have said that “at this point in the pandemic, there is not enough evidence about the effectiveness of