Genzyme Corp said it has shut down a key production facility, its Allston Landing plant, to clean viral contamination responsible for slowing down the process for making supplies of two biotech-based drugs.

The biotech company said the virus is not harmful to people but it was shutting down the facility as a precautionary measure. The company will properly clean all its equipment before re-starting the facility in July.

Supplies of bio-tech based drugs Cerezyme and Fabrazyme will be affected because of the shutdown.

Fabrazyme is used to treat an inherited disorder known as Fabry disease, while Cerezyme is used in the treatment of Gaucher disease, an enzyme disorder that can lead to liver and neurological problems.

Genzyme said it has confirmed that the virus had previously caused declines in cell productivity at the facility and at its plant in Geel, Belgium. The company said it will initiate adding steps to intensify raw material screening and viral removal processes. Meanwhile, according to reports the inventories of the drugs are not sufficient to meet global demand.

"The patients who need these therapies are our priority," chairman and CEO Henri A Termeer said in a statement. "We are confident in the quality of the products produced in Allston and in our ability to resolve the issue affecting the plant."

In another statement, BioMarin Pharmaceutical Inc of Novato, Calif said that the contamination would not Aldurazyme production which is used in the treatment of an enzyme disorder and is marketed by Genzyme.

Cerezyme was Genzyme's largest selling product while Fabrazyme was at No 3 last year and the products together accounted for about 37 per cent of the $4.6 billion of 2008 revenue of the company.

Meanwhile, the company said it would provide earnings and revenue forecasts as early as possible although it expected revenue to be hit starting August.

According to analysts if the company lost six weeks of sales of both drugs it could lower 2009 earnings per share by 28 cents to $3.30 which would be 8 per cent hit assuming the company was unable to make good the supply shortfall.

They point out that it could be a significant set back as the facility produces several of the company's key products and there were still many unknowns. They add that it appears that there are some issues with the plant that would be certain to affect the company's credibility.

The company's inventory estimates are based on US regulators continuing to allow the current supply to be sold.