US coronavirus task force response coordinator Dr. Deborah Birx said that the United States and other countries could have had a stronger initial response to COVID-19 if China had been more forthcoming about key features of the virus.

At a panel held by the Atlantic Council, a US think tank, Birx said the United States would have been more focused on identifying COVID-19 patients without symptoms if China has shared information about the frequency with which COVID-19 patients, particularly young people, are asymptomatic.

“I have to say if we had known about the level of asymptomatic spread, we would have all looked at this differently,” Birx said at the panel. “That’s usually the initial countries’ responsibility … and I think that did delay across the board our ability to really see or look for this.”

Birx said that public health officials had originally assumed that only 15 to 20% of COVID-19 patients are asymptomatic when in fact that number is at least 40%.

“We were looking for people with symptoms. We should have looked for anyone who would have been exposed,” she said.

President Donald Trump has leveled blame at China for the outbreak, saying the country should have warned the world much sooner.

China’s United States embassy told Reuters in a statement that China has been open, transparent and responsible since the pandemic broke out.

“We notified the (World Health Organisation) of the epidemic, shared the genome sequencing of the virus, carried out international cooperation and helped other countries affected, all at the earliest time possible,” the statement said. “These are plain, internationally recognized facts, which cannot be denied or erased by anyone.”

The United States saw a 27% increase in new cases of COVID-19 in the week ended July 5 compared with the previous seven days.