By Nikhila Natarajan New York, April 11 : America's top medical experts on the White House coronavirus task force Dr. Deborah Birx and Dr. Anthony Fauci pointed to encouraging signs that the US infection curve is levelling off but warned against relaxing social distancing guidelines and declaring victory too early. The doctors' comments come on a day when the world passed a grim milestone of 100,000 deaths from the pandemic and America's death toll crossed 18,000. More than 4 in 10 deaths in the US have come from New York State, which reported 777 new deaths on Friday. "You can see for the first time that in the United States we're starting to level on the logarithmic phase, like Italy did about a week ago. And so this gives us great heart," Dr. Birx said at a White House briefing on Friday. Hope springs from New York's hospitalisation rate slowing consistently throughout this week. The numbers are down to the below 300 level compared with more than 1000 per day last week. The nation's top infectious-diseases expert Dr. Fauci cautioned that the virus' trajectory decides the timeline of when social distancing rules are relaxed. "The one thing you don't want to do is you don't want to get out there prematurely and then wind up backtracking," he said as US president Donald Trump looked on. Trump has been enthusiastic about reopening the economy as soon as possible. Both Fauci and Birx have doubled down on their public messaging from the White House megaphone that social distancing does work and is blunting the curve in ways that weren't clear even a week ago. Exactly 10 days ago, the predictive model most frequently quoted by the White House had projected 100,000-200,000 total deaths in the US. Today, that projection has been revised downwards to around 61,000 deaths. The revisions reflect real time data and behaviour change in society at large. "We've never been here before. There's no literature to tell us what to expect," Birx said when asked about the sharp changes in the projections in less than two weeks. Birx and Fauci applauded the American public for complying with the mitigation guidelines now in force since March 16. US president Donald Trump said 95 per cent of the country is following along with the federal recommendations on social distancing which stop short of a national lockdown. "Last week, we really asked a lot of people in the Washington and Baltimore area to consolidate, not go out, frequently to grocery stores or pharmacies, you can really see that that's having a huge impact," Birx said. Birx warned that although the signs from New York's flattening curve are encouraging, the US has not "reached the peak". "And so every day, we need to continue to do what we did yesterday, and the week before, and the week before that because that's what in the end is going to take us up and down the other side." (Nikhila Natarajan can be reached at @byniknat) /IANS