The coronavirus epidemic is “far from over” in the Asia-Pacific region, and current measures to curb the spread of the virus are buying time for countries to prepare for large-scale community transmissions, a WHO official has said.

Even with all the measures, the risk of transmission in the region will not go away as long as the pandemic continues, said Takeshi Kasai, regional director for the western Pacific at the World Health Organization.

His warning came as the World Bank said the economic fallout of the pandemic could drive large parts of east Asia into poverty, and as the United States recorded its deadliest day yet, with another 540 deaths taking its fatalities past 3,000.

“Let me be clear. The epidemic is far from over in Asia and the Pacific. This is going to be a long-term battle and we cannot let down our guard,” Kasai told a virtual media briefing. “We need every country to keep preparing for large-scale community transmission.”

The new coronavirus first surfaced in central China in late 2019. Infections have now exceeded 770,000 cases worldwide, with the US, Italy and Spain overtaking mainland China in confirmed cases.

In a symbolic moment in the fight against the pandemic, the US navy hospital ship Comfort sailed down the Hudson into Manhattan on Monday, to the relief of cheering onlookers on New York and New Jersey’s river banks.

“It’s a war-time atmosphere and we all have to pull together,” said the New York City mayor, Bill de Blasio, who greeted the ship’s arrival at the Midtown Manhattan pier.

The ship’s 1,000 beds will treat non-coronavirus patients, including those who require surgery and critical care, in an effort to free up other medical resources. In the city’s Central Park, a field hospital of white tents with 68 beds will begin taking patients on Tuesday, according to de Blasio.

But few Americans will take solace from the statistics. On Monday, at least 540 deaths were recorded from Covid-19, taking the death toll to 3,040, according to Johns Hopkins University’s tracker, with just under 165,000 infections. Of those deaths, just under a third – 914 – were in New York City.

Donald Trump’s daily news conference featured hand-picked captains of industry praising his efforts to tackle the virus, while reporters were again chastised for asking hard questions. CNN’s Jim Acosta quoted the president’s own assertion that the virus was “very much under control”, to which Trump responded: “It’s almost a miracle the way it’s all come together, and instead of asking a nasty, snarky question like that, you should ask a real question.”

Across the US there was anger over photos of homeless people sleeping in a parking lot in Las Vegas that had social distancing markers painted on.

In China, the city of Wuhan – where the virus began – reported its seventh day in a row with no new cases, according to the country’s National Health Commission.

Despite this, World Bank said the pandemic was causing “an unprecedented global shock, which could bring growth to a halt and could increase poverty across the region”. Even in the best-case scenario, the region could see a sharp drop in growth, with China’s expansion slowing to 2.3% from 6.1% in 2019, it said.

Chinese state media reported that factory activity rebounded in March, with the Purchasing Managers’ Index, a key gauge of manufacturing activity, coming in at 52.0. This was higher than the 44.8 analysts expected in a Bloomberg survey, and up from 35.7 in February, which was the worst month since China began recording the data in 2005. A reading above 50 suggests growth in the sector.

But China’s international trade in services dropped 11.6% in January and February, with imports and exports of tourism services plunging 23.1%, citing the commerce ministry.

Elsewhere in east Asia, there were concerns over a rise in cases in the Japanese capital, Tokyo. But a government spokesman dismissed calls for the prime minister, Shinzo Abe, to declare a state of emergency. The country’s economics minister warned that shutdowns in cities such as Tokyo or Osaka could have huge consequences on the world’s third largest economy.

In South Korea, which has been hailed for its rigorous testing programme, it was announced that schools would open online classes next week, after a delayed start to the term. After a big early outbreak, the country’s daily new cases have fallen to about 100 or less, but infections from small clusters including churches, hospitals and nursing homes, as well as imported cases, continue to arise. Total infections stand at just under 10,000, with 162 deaths.

In other developments:

• The WHO said people should use face masks only if they are sick or caring for someone who is sick: “There is no specific evidence to suggest that the wearing of masks by the mass population has any potential benefit. In fact, there’s some evidence to suggest the opposite in the misuse of wearing a mask properly or fitting it properly,” the WHO’s Dr Mike Ryan said.

• Australia reported reported a sustained fall in the rate of new coronavirus infections, slowing from 25-30% a week ago to an average of 9% over the past three days.

• Mexico’s recorded 1,094 cases of coronavirus is up from 993 the day before, with 28 deaths.

• American Airlines said it plans to seek $12bn in government aid to cover payroll costs over the next six months.

• Elton John’s live music from home, which featured Billie Eilish, the Backstreet Boys, Lizzo, Alicia Keys, Mariah Carey, Lady Gaga and Tim McGraw all appearing by phone, home cameras or online platforms, raised $8m for two first responder charities.