Washington (AFP) – A top US health official on Thursday said the overall mortality rate for the novel coronavirus was estimated at one percent or less, lower than previously thought, basing the new figure on a high number of unreported cases.

It came after President Donald Trump was criticized for saying he believed the World Health Organization’s reported death rate of 3.4 percent to be “false,” based on a “hunch.”

Trump was invoking the fact the WHO figure is based on reported cases only, and as such the true lethality of the disease may only be understood better over time — a point on which health experts agree.

“The best estimates now of the overall mortality rate for COVID-19 is somewhere between 0.1 percent and one percent,” Admiral Brett Giroir, the assistant secretary of health said at a news briefing.

“That’s lower than you heard probably in many reports, why is this? Number one is because many people don’t get sick and don’t get tested — this reflects the overseas experience — so probably for every case, there are at least two or three cases that are not in that denominator.

“It certainly could be higher than normal flu, it probably is, but it’s not likely in the range of two to three percent.”

The seasonal flu mortality rate is 0.1 to 0.15 percent, said Giroir.

Trump put Vice President Mike Pence in charge of the US coronavirus response last week, amid complaints the administration had been slow to prepare for its spread.

Trump himself has been criticized for seeming to low-ball the risk, and his comments to Fox News appearing to dismiss WHO data raised eyebrows including in his own Republican Party.

“I listen to the scientists when it comes to the numbers, and I would encourage the president if he’s going to report things to make sure that the science is behind what he’s saying,” Senator Lindsey Graham told reporters.

There have been 11 reported deaths in the US and more than 130 cases in at least 14 cases with Texas reporting its first case Thursday.

A cruise ship with 21 people who have symptoms was being held off the coast of San Francisco as California, the US state with the highest number of cases, declared a state of emergency.

Thousands of people are traveling aboard the Grand Princess, the same cruise ship on which California’s first victim was thought to have contracted the virus.

The Grand Princess belongs to Princess Cruises, the company that operated the coronavirus-stricken ship held off Japan last month on which more than 700 people tested positive.