Typhoid vaccine declared a success.

Typhoid vaccine declared a success

Taking a different approach to making vaccines against typhoid fever has produced a winner, scientists announced last week. Researchers at the National Institute of Child Health and Human Development (NICHHD) in Bethesda, Md., reported that a vaccine made from a polysaccharide capsule surrounding the typhoid bacterium appears to be superior to current vaccines made from whole Salmonella typhi bacteria.

Scientists at NICHHD collaborated with others in Nepal, Sweden and France during a pilot study and a subsequent clinical trial of the NICHHD-developed vaccine. The two studies involved more than 7,000 Nepalese, who live in an area of the world seriously affected by typhoid fever. Spread through unsanitary conditions, typhoid fever attacks an estimated 50 million people in Asia each year, with high death rates. But currently available vaccines require multiple doses, have side effects and protect for a limited time.

As reported in the Oct. 29 NEW ENGLAND JOURNAL OF MEDICINE, results from the recent Nepal studies indicate that a single injection of the new vaccine lowered the risk of developing the disease approximately four-fold, compared to those not immunized. Such protection is as good as or better than present vaccines. Although the new vaccine produced protective antibodies in only 75 percent of those tested, the authors conclude it is preferable, with fewer side effects.