How do they know the numbers of infected are so high, when the reported cases are so low?  Sandy

http://biz.yahoo.com/rf/010514/n14244524.html

U.S. approves combination Hepatitis A, B vaccine

(UPDATE: previously Philadelphia, recasts with FDA comments, detail)

WASHINGTON, May 14 (Reuters) - U.S. regulators said Monday they approved a combination hepatitis vaccine made by GlaxoSmithKline Plc (quote from Yahoo! UK & Ireland: GSK.L) (NYSE:GSK - news) to protect people from both the A and B strains of the infectious liver disease.

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The Food and Drug Administration approved the Twinrix vaccine for individuals 18 years and older to allow people at high risk to be immunized against both viruses simultaneously.

“Clinical trials of Twinrix...demonstrated that the combination vaccine was as safe and effective as the already licensed separate vaccines,” the FDA said in a statement.

GlaxoSmithKline said hepatitis A and B are the most common vaccine-preventable diseases in travelers.

Twinrix would benefit people traveling to high-risk hepatitis areas in the developing world, the British drug company said, as well as men who have sex with other men, chronic liver disease patients, health-care personnel, personnel and residents of institutions, and military personnel.

Hepatitis A can be contracted from contaminated food or drinking water.  Hepatitis B is spread through contact with infected blood or other body fluids, often as a result of contaminated needles or unprotected sex with an infected person.

Both diseases can produce symptoms that include fever, weakness and jaundice. While hepatitis A is rarely fatal, hepatitis B can result in chronic hepatitis, cirrhosis and liver cancer.

Each year, 125,000 to 200,000 Americans are infected with hepatitis A, and 140,000 to 320,000 are infected with hepatitis B, the company said. 

ALL INFORMATION, DATA, AND MATERIAL CONTAINED, PRESENTED, OR PROVIDED HERE IS FOR GENERAL INFORMATION PURPOSES ONLY AND IS NOT TO BE CONSTRUED AS REFLECTING THE KNOWLEDGE OR OPINIONS OF THE PUBLISHER, AND IS NOT TO BE CONSTRUED OR INTENDED AS PROVIDING MEDICAL OR LEGAL ADVICE.  THE DECISION WHETHER OR NOT TO VACCINATE IS AN IMPORTANT AND COMPLEX ISSUE AND SHOULD BE MADE BY YOU, AND YOU ALONE, IN CONSULTATION WITH YOUR HEALTH CARE PROVIDER.