However, Chiron is still unsure when the inspections may take place, or indeed when it may be able to regain the manufacturing license for its Fluvirin flu vaccine. The company also said it will be unable to give any full-year earnings guidance until the issue is resolved.
Speaking at the JPMorgan Healthcare Conference in San Francisco, US, chief executive Howard Pien said Chiron anticipates that the UK Medicines and Healthcare products Regulatory Agency (MHRA), accompanied by US Food and Drug Administration (FDA) inspectors as observers, will conduct a series of inspections of the manufacturing facility.
"With this regulatory process, the remediation effort may advance toward the restoration of the facility's license, as successive phases of manufacturing pass inspection by the MHRA," he said. Chiron could receive sequential clearances to operate in certain areas as remediation continued in others.
Chiron's license to make the vaccine at the Liverpool was suspended after contamination problems that compromised the sterility of its production process. The plant supplied a sixth of the UK market for flu vaccines, but the suspension was particularly felt in the US, as Chiron was due to supply fully half the country's order for flu vaccines in the 2004-2005 season.
And last month, the MHRA extended the halt on production until the beginning of April, and the FDA sent the firm a warning letter about the plant, raising concerns that Chiron may be unable to meet commitments for the next flu season.
Meanwhile, the problems are reported to be having a knock-on effect on other products made by Chiron at the Liverpool plant. UK supplies of the potent painkiller diamorphine, used in patients who are very ill with diseases such as cancer, are said to be running low. Chiron is the main supplier of the drug in the UK - supplying 50 to 60 per cent of the market - and has said it does not expect more stock to be available until the end of the first quarter.
The other major supplier of diamorphine in the UK is Wockhardt, which said it is working to increase supply and should have more stocks available by the end of the month.
Finally, in another twist to the flu vaccine tale, the Sunday Times newspaper has suggested that lawyers in the US are investigating how much the management of the company formerly operating the plant - PowderJect (acquired by Chiron in 2003) - knew about the problems at the plant.
US lawyer Milberg Weiss is claiming that problems surrounding the site date back to at least the time of the takeover.