Novartis said it is considering acquiring Swiss vaccines company Berna Biotech, which agreed earlier this month to be bought by Dutch biotechnology company Crucell in an all-share purchase. "No assurance can be given" that it will make an offer for Berna, Novartis said in a statement, although it is conducting due diligence on the vaccines firm "in order to prepare a potential competing cash offer." Crucell's all-stock exchange offer was valued at 591 million Swiss francs, or $458 million. Berne, Switzlerland-based Berna said its board of directors decided to grant due diligence to a second potential bidder and will inform "in due time" whether any new offer is superior to Crucell's. If Novartis moves ahead with the purchase, it said it may combine Berna's operations with those of Chiron, the U.S. vaccines company Novartis is currently in the process of acquiring. "The combination of Berna and Chiron would offer complementary geographic coverage and product ranges," Novartis said. The Swiss drug maker would also gain access to Berna's proprietary technology. Berna's portfolio includes inoculations against hepatitis A and B, influenza and typhoid fever.