Residents of Wuhan have been warned to stay indoors and strengthen protection measures, a few days before travel restrictions on the city at the centre of the pandemic are scheduled to be lifted.

The city’s top official urged vigilance as authorities sought to ward off a second wave of infection from incoming travellers, while also easing some of its stringent containment measures.

China has reported more than 81,600 cases of the virus since the outbreak began, including 3,322 deaths, but the level of transparency around the figures has been questioned. Until this week China’s national health commission was not including people who tested positive but showed no symptoms in its tally. On Friday it reported 31 new confirmed cases, including two locally transmitted infections. Four people died, all of them in Wuhan.

While the number of daily cases has dropped dramatically since February, Wang Zhonglin, Wuhan’s Communist party chief, said the risk of a rebound in the city’s epidemic remained high due to both internal and external risks and it must continue to maintain prevention and control measures.

Wuhan has eased restrictions over recent weeks and authorities have said curbs on travel will lift on 8 April, for those with the green “health code”.

China will hold national mourning on Saturday for 14 “martyrs” who died while responding to the pandemic. National and foreign embassies and consulates will fly flags at half mast and all public entertainment will stop. At 10am there will be three minutes’ silence.

Li Wenliang is among the 14 health workers and police declared to be “martyrs” for their efforts. The Chinese doctor was reprimanded by authorities for “spreading rumours” after he sought to warn colleagues about the emergence of Covid-19 in December, but in March an investigation into his death exonerated Li and recommended the reprimand be withdrawn.

The pandemic has reached new heights across the world – in particular in the US where authorities have reported nearly 240,000 infections and 5,798 deaths, according to the Johns Hopkins university tracker.

More than a million people have been diagnosed with Covid-19 and more than 51,400 people have died.

Donald Trump has ordered defence forces to start making ventilators, after weeks of resisting calls to broadly implement the Defence Production Act. The president has blamed the states for a lack of medical supplies, saying they should have stockpiled and the federal government was “a back-up, not an ordering clerk”.

New York is said to be at risk of running out of ventilators in less than a week. The governor, Andrew Cuomo, has been among many state leaders saying they were desperate for assistance and complaining that states have to bid against each other and federal agencies just to secure supplies. US authorities were expected to release new guidelines on the wearing of masks, amid conflicting recommendations and policies between different countries.

In other developments around the world: