H.R.4200: To amend the Internal Revenue Code of 1986 to provide a tax credit for medical research related to developing qualified infectious disease products.

Amends the Internal Revenue Code to allow a general business tax credit for 50% of expenses paid for research and development of any qualified infectious disease product. Defines "qualified infectious disease product" as any antibiotic drug, antiviral, diagnostic test, biological product, or vaccine developed to treat, detect, prevent, or identify certain pathogens. Terminates such credit after 2012.