Emerging Disease Threat Prompts Large DoD Vaccine Study

San Diego, California, August 24, 2000—

Investigators from five different Navy, Army, and Marine Corps commands, the Centers for Disease Control and Prevention, and the Mayo Clinic and Foundation, in collaboration with Wyeth Lederle Vaccines, are about to embark on one of the largest clinical trials in military history. Led by investigators at the Naval Health Research Center (NHRC) in San Diego, the study team plans to conduct a multi-centered clinical trial to assess the effectiveness of a pneumococcal polysaccharide vaccine among 191,000 military personnel.

"This study will help not only U.S. military personnel, but it also has the potential to help improve the health of other young adult populations at high risk for respiratory tract infections," says NHRC’s Captain Gregory Gray, the principal investigator of the study.

The study vaccine, first developed more than 25 years ago, has a very safe track record but is seldom used in healthy young adult populations. It is designed to protect against infection from 23 serotypes of Streptococcus pneumoniae (pneumococcus) and has been most often used among elderly populations and persons with chronic medical conditions. With the exception of one recruit training facility and two Special Forces training sites, the vaccine has not been routinely administered to new military personnel.

"When it has been used, its effectiveness could not be evaluated because control groups were not used," states Dr. Gray.

The investigators will determine the benefit of using the vaccine by comparing the incidence of pneumonia and acute respiratory disease between military trainees randomly assigned to receive either vaccine or placebo injections. They will also measure loss of training time due to respiratory illness between the two groups. "This study is very important because it will provide sound epidemiological evidence necessary to make policy decisions regarding the routine use of the pneumococcal vaccine among military personnel." says the study coordinator, Carolyn Baker of NHRC.

Recent military outbreaks of pneumococcal pneumonia and increased antibiotic resistance have led military public health officials to consider employing the vaccine among training populations.

"The question," says Dr. Gray, "is whether the reduction in illness is worth the cost."

Now, thanks to a competitive research grant the team received and the collaboration of Wyeth Lederle Vaccines who is donating vaccine products, the team will be able to answer this important question.

"The U.S. military is one of the few places where such a study can be performed," reports Lieutenant Commander Margaret Ryan, a physician epidemiologist, also of NHRC. "We have populations at high risk for pneumonia, at sites where we can follow them closely. These attributes will be important in conducting such a large, complex study."

Military data show that while recruit training populations account for only 5% of the U.S. military populations, they represent 65% military hospitalizations for pneumonia.

The pneumococcus has caused epidemics of pneumonia in recruits and active-duty members, sometimes causing death, but always affecting force readiness and placing a strain on medical facilities. In the winter of 1989, a pneumococcal pneumonia outbreak among U.S. Marines in Southern California led to 124 hospitalizations and resulted in the use of thousands of vaccinations and painful penicillin injections. In the late 1990s, two pneumonia outbreaks (thought to be due to the pneumococcus) occurred among Army Special Forces trainees, affecting more than three dozen servicemen. But these outbreaks underrepresented the true impact of this pathogen, say the investigators, since the pneumococcus is difficult to detect without special tests. The research team will use such special laboratory tests, coupled with surveillance for outpatient and inpatient illness, to determine if the vaccine reduces disease.

In addition to the military outbreaks, increasing antibiotic resistance among pneumococcal bacteria in the U.S. has caused investigators to look to the vaccine to prevent infection rather than relying on antibiotics to treat it. NHRC has been conducting surveillance for pneumococcal isolates from eight different military referral hospitals in the U.S. Thirty-three percent of sterile site isolates displayed full or partial resistance to penicillin, and 23% of isolates exhibited resistance to multiple antibiotics that were very effective 10 years ago. It is remarkable, say the study investigators, that penicillin resistance has become so common in such a short time period.

The study is scheduled to begin in the fall of 2000, first among volunteers at the Marine Corps Recruit Depot, San Diego. Shortly afterward, the study will begin at Fort Leonard Wood, MO; Naval Recruiting Training Center, Great Lakes, IL; and Fort Jackson, SC. Investigators at the four study sites include Major Keith Baugh, Fort Leonard Wood, MO; Major Xiomara Brown, Fort Jackson, SC; Lieutenant David Cute, Naval Recruit Training Center, Great Lakes, IL; and Lieutenant Manuel Leal, Marine Corps Recruiting Depot, San Diego.

The study will follow strict federal guidelines for medical research. All participants will be given detailed information regarding the vaccine and study design. They will have the opportunity to ask questions and may decline to participate without any effect on medical care, training, or compensation.

This study has been recommended by the prestigious Armed Forces Epidemiological Board, a panel of nonmilitary experts, and it received an excellent scientific merit score upon review by the American Institute of Biological Sciences.