The US surgeon general said he was “optimistic” about America’s fight against the coronavirus after signs that social distancing across the country was working.

Jerome Adams told ABC’s ‘Good Morning America' that it was “absolutely” his expectation that the death toll would fall below the expected worst-case scenario predicted by some models, and that there was "a light at the end of this tunnel."

“The good news is that when you look at Washington and California, and even New York and New Jersey, they have truly started to flatten their curves,” he said on Tuesday.

“It’s going to be a hard and tough week, but the American people have the power to change the trajectory of this epidemic if we come together like we have after past tragedies in this country,” he added.

Last week, the White House coronavirus task force projected a death toll of 100,000 to 240,000, saying containing deaths to that range was possible if strict social distancing measures were respected.

In New York, the epicentre of the US coronavirus outbreak, the city’s mayor Bill de Blasio also hinted at signs of progress.

"The number of people showing up in our hospitals who need a ventilator - that situation has improved a bit in recent days," he said.

"For the first time in many days, we did not see a major increase in the number of ventilators needed" in hospitals that have been bearing the brunt of the outbreak like Elmhurst Hospital in Queens and Lincoln Medical Center in the Bronx, Mr de Blasio added.

Mr Adams said the next 30 days would be crucial in stopping the spread of the outbreak.

“The most important thing for the American people now is to really focus on these 30-days-to-slow-the-spread guidelines because we have proof that they work,” he said. “But we need you all to cooperate, we need you to continue doing your part — and most people actually are. Over 90 percent of the country is actually doing the right thing right now.”