While the vast majority of infections and deaths have been in China, in particular Hubei, there have been almost 450 cases in about 24 nations and territories outside of China, and three deaths. "We're a little disappointed in the lack of transparency coming from the Chinese, these numbers are jumping around. there was some surprise", he told reporters.
Under criticism at home over the handling of the crisis, China's Communist Party sacked two top-ranking officials in Hubei and replaced them with senior cadres with security backgrounds.
The virus is believed to have emerged late previous year at a seafood market in the city of Wuhan that was illegally selling wildlife.
US President Donald Trump praised China over its response and said Washington was working closely with Beijing.
Authorities in Hubei on Thursday started counting patients who were "clinically diagnosed" via lung imaging, in addition to those who undergo lab tests.
The measure came as Egypt confirmed the first coronavirus case in Africa. The new block of clinical cases may date back days or weeks.
"We've seen this spike in the number of cases reported in China, but this does not represent a significant change in the trajectory of the outbreak."
There was good news for passengers on another cruise ship that was finally allowed to dock in Cambodia after being rejected by five nations over fears of the virus, even though no cases were reported on board.
Hubei province is now including cases based on a doctor's diagnosis and before they have been confirmed by laboratory tests.
"There have been some backlogs in testing and this is also going to help in ensuring that people get adequate care", Ryan said.
The nationwide toll rose to 1,380 on Friday, although 108 deaths in Hubei were removed from the tally after being double-counted.
The number of novel coronavirus cases has risen to more than 64,000 worldwide, after China reported another major increase at the epicenter of the outbreak following a change in how authorities there diagnose cases.
They are the first group of dozens of older passengers expected to get off the vessel before their 14-day quarantine period ends on February 19 to reduce risks of their health deteriorating.
Some 26 billion Chinese yuan (US$3.7 billion) has been spent on medical equipment, protective gear and improving conditions in medical facilities, said Ou Wenhan, a finance ministry official.
"This outbreak could still go in any direction", WHO Director-General Tedros Ghebreyesus said, the BBC reported on Thursday.
"Investors will surely avoid Asia for the time being and will shift funds to the United States, geographically the most separated from the region", said Norihiro Fujito, chief investment strategist at Mitsubishi UFJ Morgan Stanley Securities.
Kudlow's comments contrasted with Trump's apparent confidence in China, with the U.S. leader telling a radio show that Xi is "extremely capable" and that the USA was "working with them" and "sending a lot of people".
The number of new daily infections reported by Chinese authorities hit a peak last week at close to 4,000.
Several countries have banned arrivals from China, while major airlines have halted flights to and from the country.
Only two patients have died from the infection outside of China, according to WHO.