Vanderbilt study to test effectiveness of vaccine
Posted: Wednesday, November 7, 2012 8:00 pm
Vanderbilt University Medical Center is taking part in a national study to test in older adults the use of a vaccine designed to protect children against a common cause of pneumonia.
The Vanderbilt Vaccine Research Program is recruiting 147 adults older than 55 to participate in the study, funded by the National Institutes of Health (NIH), that will compare two different dosage levels of a “conjugate version” of the vaccine to protect against streptococcus pneumoniae, or pneumococcus.
The goal is to determine if a higher dose of the vaccine originally designed for young children will elicit a stronger immune response in older adults, even those who have been vaccinated with the currently recommended vaccine.
Pneumococcus causes approximately 364,000 cases of pneumonia in people older than 65 each year, a troublingly high rate despite widespread vaccination. To address this, booster shots have been recommended at the discretion of the physician in adults at high risk for pneumonia.
At Vanderbilt’s Internal Medicine Practice, 78-year-old Cecil Sanders recently agreed to a booster shot of the currently recommended vaccine for adults older than 65, called Pneumovax.
“My doctor advises me to get the flu shot every year, and I listen to him. I haven’t been sick one day, so if he says I should get it, I’ll get it,” Sanders said.
Sanders’ physician, James Powers, M.D., a Vanderbilt geriatrician, said because Sanders’ poorly controlled diabetes increases his risk for infection, it is reasonable to recommend a five-year booster of Pneumovax, but he is glad the current study will examine another option.
“It has been very effective against meningitis and sepsis, but it has not had a major impact on pneumonia,” Powers said. “So as far as pneumonia, I give it, but I don’t strongly believe in it.”
Pneumovax, which has been in use for 30 years, provides protection against 23 of the most common strains of pneumococcus and is very effective against bloodstream infections, but not as effective against pneumonia. The vaccine used in children, known as PCV13, or by the brand name Prevnar, provides protection against only 13 strains of the bacteria, but is prepared by combining, or conjugating, it with diphtheria protein, to stimulate a more powerful immune response.
The vaccine works extremely well in children.
“Recent data suggest older adults respond better to the conjugate and have better memory for the conjugate than for the old pneumococcal vaccine,” said Kathryn Edwards, M.D., Sarah H. Sell and Cornelius Vanderbilt Professor of Pediatrics and director of the Vanderbilt Vaccine Research Program.
Earlier this year, Prevnar was approved for adults older than 50 under the Food and Drug Administration’s Accelerated Approval Pathway, however it is unknown which dose would be most effective in preventing disease.
Edwards is the principal investigator for Vanderbilt’s arm of the study being conducted at six medical centers across the nation. Adults age 55 to 74 will be randomized into two groups. The first group will include those who have never been vaccinated against pneumonia. They will receive a single injection of the PCV13 vaccine at the standard dose of 0.5 milliliters. The second group will include adults who were previously vaccinated with the standard vaccine three to seven years earlier.
Within this group, adults will be further randomized to receive either one injection, or to receive a double dose by receiving two injections, one in each arm. Researchers will evaluate participants’ immune responses via blood samples over 18 months.
Information about the clinical trial is available at http://www.clinicaltrials.gov under the identifier NCT01654263.
For more information about participating in Vanderbilt’s trial, call 322-2730. Published in The Messenger 11.7.12