Biostatisticians demonstrate method to bolster accuracy of vaccine studies.

2003 SEP 3 - (NewsRx.com & NewsRx.net) -- Is my illness serious enough to warrant a doctor visit? Do I have the flu or the common cold? These mundane questions posed by millions every year during flu season bedevil scientists who study influenza vaccines and can obscure the effectiveness of a trial vaccine.

Scientists from the Rollins School of Public Health at Emory University have been exploring ways to measure vaccine effectiveness accurately, despite two persistent problems that threaten to confound statistical analysis: bias in reporting illness and nonspecific definitions of disease.

The research, conducted by lead authors and Emory epidemiologists M. Elizabeth Halloran, MD, DSc and Ira Longini, PhD, was published in the American Journal of Epidemiology. Using validation sets, a technique for verifying the reliability of epidemiological data, they hope to assist researchers studying vaccines against diseases like flu, as well as diseases such as malaria prevalent in developing countries.

The Emory scientists collaborated with investigators at Baylor College of Medicine and Texas A&M Medical School to study the effectiveness of a nasally administered influenza vaccine. The study covered children in the Temple-Belton area in Texas in the years 2000-2001. The trivalent, cold-adapted, influenza vaccine was licensed by the U.S. Food and Drug Administration (FDA) in June for individuals age 5-49, and is sold by MedImmune Vaccines under the name FluMist.

When doctors are studying the effectiveness of a drug or a vaccine, the gold standard remains the randomized, double-blind study. That helps to prevent the prejudices of doctors and patients from biasing the research. The gold standard for investigators studying influenza vaccines is to take culture samples from all patients, then use laboratory tests to check for the influenza virus's presence and strain.

"I divide cases into what I call 'fake flu,' and 'genuine flu,'" said Halloran. "'Nonspecific case definition' means not being able to know the difference. That can hide how effective a vaccine is, because it looks like people are still getting sick, even when the vaccine may be working."

Pathogens that can masquerade as the flu ...