Vaccines are an effective way to help prevent common illnesses, such as influenza and pneumonia, but senior citizens don't receive the same protective benefit from standard vaccines as younger recipients. Could part of the reason be as simple as the fat content of their arms?
That is one of the questions researchers at the University of Maryland School of Medicine hope to answer as they embark on a new study in which persons age 65 and older receive licensed Hepatitis B vaccinations in three separate injections over a six-month period.
The objective of the study is to monitor the body's response to the vaccine when it is injected in the muscle versus the fat of the upper arm.
This clinical trial is one of several planned studies sponsored by the National Institute of Allergy and Infectious Diseases and the National Institutes of Health. The University of Maryland School of Medicine and the Baltimore Veterans Affairs Medical Center, have been awarded a five-year contract by the NIH to evaluate vaccines and various therapeutic agents for infectious diseases in older adults, according to Dr. Robert Edelman, principal investigator of the program grant. The findings should improve the understanding of how aging impacts the immune system and the body's responses to vaccines and infections.
Because individuals age 65 and older are at higher risk of serious illness from tetanus, influenza and pneumococcal disease, routine immunization is recommended. Unfortunately, compared with younger persons, the elderly do not develop robust immunological responses to these vaccines. One objective of the study is to discover why that occurs on a physiological and molecular level and to try to overcome this natural weakening of the immune system observed in the elderly with novel vaccines and immunization strategies.
"The immune system, made up of lymph nodes, the spleen, white blood cells and antibodies, seems to weaken with age," says Dr. Mark Heuser, principal investigator of the Hepatitis B vaccine study. "Because older people often have more fat under their skin and less muscle, we wonder if the unplanned injection of a vaccine into fat is responsible for the poor response seen in older people to the Hepatitis B and other vaccines intended for injection into muscle."
"The purpose of this study is to try to discover if the location where a vaccine is placed, fat or muscle, affects how well the body will respond to the vaccine in older adults. And if location is important, then we hope the information from this study will enable older people to respond better to all vaccines developed for injection into muscle."
Over the past 50 years, the widespread use of vaccines has been a major contributing factor in improving the health of people worldwide. Diseases like polio have been eliminated and others, such as German measles, diphtheria and whooping cough, have been significantly reduced. Immunization programs for the elderly have not been as successful, however. Despite available vaccines, deaths from preventable diseases including influenza and pneumococcal pneumonia persist in the elderly.
In the study, 50 volunteers will receive a series of three doses of licensed Hepatitis B vaccine administered over a six-month period. The volunteers will be chosen at random by computer to have a shot of the vaccine either in the fat or the muscle of the upper arm. All volunteers will receive a body scan that determines total body fat, muscle and bone density levels. A CT scan of the shoulder of each volunteer will determine the length of needle used. They will be followed for one year.
The Hepatitis B virus is an important cause of liver disease in humans with approximately 200,000 new cases in the United States and 10 to 20 million infections worldwide annually. The Hepatitis B virus may be transmitted by blood transfusion, dirty needles, exposure to body fluids from someone who is infected and from mother to child. In addition to a short-term illness caused by the Hepatitis B virus, up to 20 percent of infected individuals go on to develop chronic or long-term disease. About 10 percent of those with chronic liver disease develop liver cirrhosis or liver cancer.
Although adults age 65 years and older represent 13 percent of the American population, fewer than 3 percent of acute cases of Hepatitis B occur among elderly persons. However, once infected with the virus, elderly patients often become sicker and more prone to develop chronic infection. The researchers say the risk of Hepatitis B virus for seniors may increase because people are staying active longer and that could increase their exposure. More than 21 percent of community dwelling adults over age 60 demonstrate evidence in the blood of previous hepatitis infection.
Potential candidates can call 410-605-7000 ext. 6634 to enroll in the program.
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