SRI International, an independent non-profit research and development institute, is seeking healthy fraternal and identical twin pairs for the second year of a flu vaccine study sponsored by the National Institutes of Health. This year's vaccine covers both the seasonal and the H1N1 flu. The goal of the Stanford University-led study is to identify immunological responses and develop more effective flu vaccines.

"Influenza is a major cause of illness and is one of the leading causes of death worldwide.  Understanding how the influenza virus causes disease could help us develop even better vaccines and other preventive measures," said Yvonne Maldonado, chief of Paediatric Infectious Disease at Lucile Packard Children’s Hospital at Stanford.

Only twins who did not participate in last year's study are eligible to join. All volunteer participants will receive compensation and the approved influenza vaccine given to the public.

The Twin Research Registry at SRI International is seeking volunteers who are within easy driving distance to Stanford University.

"Volunteers who are able to give their time in order to help scientists conduct health studies and determine more effective treatments are extremely valuable and appreciated," said Gary E Swan, director of SRI's Center for Health Sciences, which is partnering with Stanford to evaluate results from twin pairs who participate in the flu vaccine study. "Over the years, twin volunteers have contributed to greater understanding of genetic influences on health. We hope that twin pairs will see study participation as an opportunity to protect themselves from the flu and help advance research."

Volunteers can join the Twin Research Registry at SRI International, a valuable science resource that reflects the diverse population of the region. The registry was established in 1995 by SRI's Center for Health Sciences, and currently includes more than 2,600 adult twin registrants. Registry members have participated in studies focusing on the pharmacokinetics of nicotine, metabolism of commonly used medications, genetic susceptibility to cancer-causing chemicals, and sleep patterns in young twins.

Serving government and commercial clients in the health arena, SRI's Center for Health Sciences uses a multidisciplinary research approach to address complex challenges that arise at the interface of the basic sciences, clinical medicine, health care economics, and the regulatory and legal environments.

Silicon Valley-based SRI International is one of the world's leading independent research and technology development organizations.

Ranked as one of the nation's best paediatric hospitals by US News & World Report, Lucile Packard Children's Hospital at Stanford is a 312-bed hospital devoted to the care of children and expectant mothers.