Anthony Fauci said Thursday the coronavirus vaccine "cavalry" is coming but urged the public not to let down its guard, and called for a stronger WHO to ward off future pandemics.Fauci, a world-leading expert on infectious diseases who has been at serious odds with President Donald Trump over Covid-19, said that after Pfizer's vaccine, another is "literally on the threshold of being announced".Moderna, which is co-developing its vaccine candidate with the US National Institutes of Health, says it is close to reaching a threshold in trials to apply for an emergency use authorisation from US regulators."The cavalry is coming, but don't put your weapons down," Fauci said by video-link to the Chatham House international affairs think-tank in.