The Daily Star's FREE newsletter is spectacular! Sign up today for the best stories straight to your inboxCovid-19 should be a "wake up call" for future diseases even more severe than the current pandemic, the World Health Organisation (WHO) has warned.More coronavirus patients are in hospital beds in England than ever before yet Dr Mark Ryan, the head of the WHO emergencies programme, says the virus might not even be "the big one".Dr Ryan revealed on an online briefing that new "emerging" diseases may prove to have higher fatality rates that Covid-19, which he admitted would "come as a shock to some people".However, he did not say how infectious these future diseases may be.He said: "This pandemic has been very severe, it has spread around.