President Rodrigo Duterte has announced a month-long lockdown of the whole of Metro Manila as the Philippines looks to contain the spread of Covid-19, adding that he might call on China to help deal with the outbreak.Land, domestic air, and domestic sea travel to and from the National Capital Region will be suspended from Sunday to April 14, while mass gatherings have also been banned, according to local media.In a speech on Thursday night, Duterte also said Chinese President Xi Jinping had…