The campaign targets the bribing of doctors in drug and medical equipment sales and marks a sharp escalation of an anti-corruption drive in the sector that started years ago. The latest campaign has sent a chill through the sector, pummeling healthcare stocks and prompting some firms to cancel IPOs.

"We see a recovery in terms of engagements ... we see an improvement in that area," Zafer Unluer, China president of U.S. healthcare company Organon, told Reuters on the sidelines of an industry event in Shanghai.

"It is still as not high as before, but we see a bit of a balancing act."

The anti-graft drive initially caused huge business disruptions and many multinational pharmaceutical firms lost engagement with hospitals, executives said.

"We've seen some disruption in the ability of our medical representatives to visit hospitals, in our ability to implement some medical application activities," Larry Merizalde, China CEO of South African drugmaker Aspen, told Reuters.

Barclays said in a recent note that AstraZeneca was also "facing challenges from the healthcare anti-corruption investigations in China, reducing AZN's access to physicians in the region as well as having some negative impact on prescription volumes".

A spokesperson for AstraZeneca declined to comment as the company reports quarterly results later on Thursday.

The two executives said the overall mood, however, had improved over the past two months following communications such as a National Health Commission Q&A and a presentation from a government official.

"Over the last month, since the latest announcements from the government to clarify the objectives of this anti-corruption policy, we see that overall activities are coming back to normal," Merizalde said.

China is one of the biggest healthcare markets for global healthcare companies but their business sentiment has turned fragile this year due to factors including the anti-graft drive.

(Reporting by Andrew Silver; Editing by Miyoung Kim, Robert Birsel)

By Andrew Silver