CHIR Chiron (MM)

FLUVIRIN Vaccine Must Receive Supplemental Regulatory Approvals and Annual Formal Product Release Before Delivery to Customers Chiron Corporation (Nasdaq:CHIR) today announced that the U.S. Food and Drug Administration (FDA) has communicated the results of the FDA's July 2005 GMP (Good Manufacturing Practices) inspection of Chiron's Liverpool facility, which manufactures FLUVIRIN(R) influenza virus vaccine. The FDA found Chiron's responses and proposed corrective actions to the FDA inspection observations, which the FDA issued on a Form 483 at the close of the nine-day inspection of the Liverpool facility, to be "generally acceptable." This outcome, coupled with the conclusion by the UK Medicines and Healthcare products Regulatory Agency (MHRA) in March 2005 that Chiron could conduct operations in accordance with GMP, means that Chiron may proceed with its efforts to return FLUVIRIN vaccine to the U.S. market for the 2005-2006 influenza season. Production of FLUVIRIN vaccine, which is currently underway, continues. "The FLUVIRIN remediation plan called for unprecedented communication and cooperation between the FDA and the MHRA. Chiron has now achieved a key milestone in this remediation effort. We are grateful for the direction and guidance the regulatory agencies have extended to us throughout this process, and we are proud of the dedication our employees have demonstrated in working toward this accomplishment," said Howard Pien, CEO of Chiron. "We remain focused on our objective of delivering FLUVIRIN vaccine to the U.S. market in support of public health efforts to prepare for the upcoming influenza season." Chiron's remediation plan introduced a number of improvements to FLUVIRIN vaccine facilities, equipment and processes; therefore, Chiron must receive supplemental approvals from the FDA in response to filings of these changes before the company can supply FLUVIRIN vaccine to the U.S. market. In addition, Chiron's ability to deliver FLUVIRIN vaccine to the U.S. market will depend upon successful production and final testing of the vaccine, as well as release of the vaccine by the FDA. Chiron also expects that the MHRA may again inspect Chiron's Liverpool facility before the company commences shipment of FLUVIRIN vaccine. The FDA will evaluate the implementation and effectiveness of Chiron's corrective actions and assess the company's overall compliance at the agency's next routine GMP inspection of the facility. About Chiron Chiron delivers innovative and valuable products to protect human health by advancing pioneering science across the landscape of biotechnology. The company works to deliver on the limitless promise of science and make a positive difference in people's lives. For more information, please visit www.chiron.com. This news release contains forward-looking statements, including statements regarding supply of FLUVIRIN(R) influenza virus vaccine that Chiron expects to deliver in the 2005-2006 influenza season, regulatory approvals, improvements to manufacturing facilities, product development initiatives, and product marketing, that involve risks and uncertainties and are subject to change. A discussion of the company's operations and financial condition, including factors that may affect its business and future prospects that could cause actual results and developments to differ materially from those expressed or implied by these forward-looking statements, is contained in documents the company has filed with the SEC, including the Form 10-K for the year ended December 31, 2004, and the Form 10-Q for the quarter ended June 30, 2005, and will be contained in all subsequent periodic filings made with the SEC. These documents identify important factors that could cause the company's actual performance to differ from current expectations, including, among others, additional adverse developments resulting from the suspension of Chiron's UK license to manufacture FLUVIRIN vaccine from October 5, 2004, through March 2, 2005, the announcement of such suspension and the litigation and investigations relating to those matters, the outcome of clinical trials, regulatory review and approvals, manufacturing capabilities, intellectual property protections and defenses, litigation, stock-price and interest-rate volatility, marketing effectiveness, and the severity of the 2005-2006 influenza season. In particular, there can be no assurance that additional issues with respect to FLUVIRIN vaccine or Chiron's manufacturing generally will not arise in the future, or that Chiron will be able to cover vaccine shortfalls, resume sale of FLUVIRIN vaccine for the 2005-2006 influenza season, increase sales of existing products, successfully develop and receive approval to market new products, or achieve market acceptance for such new products. The company may face additional competition in the influenza market in the future and challenges in distribution arrangements as a result of vaccine developments. In addition, the company may engage in business opportunities, the successful completion of which is subject to certain risks, including approval by Novartis AG, regulatory approvals and the integration of operations. Chiron does not undertake an obligation to update the forward-looking information the company is giving today. NOTE: FLUVIRIN is a registered trademark of Chiron.