Treat seniors when they are young for better adult immunization
By Deborah Gesensway
You would never treat your grandparents like children, but since the effectiveness of vaccines tends to dissipate with age, some experts contend that greater emphasis on vaccinating children may be the best way to protect seniors against disease.
Some studies have shown that the pneumococcal, Lyme disease and hepatitis vaccines don't work as well in older people due to a phenomenon called immune senescence, the waning of immunity with age. In addition older people tend to have many comorbidities that can interfere with immunizations. The elderly, such as those living in nursing homes, are often exposed to more communicable diseases, and may have poor nutrition and other risk factors that place them at increased risk of poor outcomes.
Exacerbations of diseases ranging from chronic obstructive pulmonary disease to cardiovascular disease may be minimized in the elderly if more children are immunized against influenza, said Kevin P. High, FACP, Professor of Medicine and Chief of the Section on Infectious Disease at Wake Forest University School of Medicine in Winston Salem, N.C. Several epidemiologic studies now suggest that immunizing children reduces transmission of influenza to adults, thereby providing protection that may be even greater than the benefits derived by immunizing older adults themselves.
For example, he said, giving a conjugated form of the pneumococcal vaccine to children has significantly reduced rates of invasive pneumococcal disease in adults over age 50. For adults over the age of 50, however, a number of smaller studies in which older adults were given the protein-conjugated type of pneumococcal vaccine have not shown an increase in protection over the less expensive polysaccharide vaccine.
"The best strategy at least for now is to immunize older adults with the polysaccharide vaccine while kids get the conjugated one."
—Kevin P. High, FACP
"We all know we get sick from our kids," Dr. High said. The data "suggest that the best strategy, at least for now, is probably to immunize older adults with the polysaccharide vaccine while kids should receive the conjugated vaccine to decrease the risk children will give pneumococcus to older adults."
Dr. High led a session about "Immunity and Vaccine Responses in Older Adults" at the Infectious Diseases Society of America's (IDSA) annual meeting in Toronto last fall.
Challenges for adults
For some vaccines, however, questions remain about the effect of childhood immunization on older adults, he said. The varicella vaccine has greatly reduced chicken pox in children, but it is possible exposure to natural chicken pox was previously a mechanism whereby immunity was boosted in older adults, perhaps reducing the risk of zoster (shingles). It is possible that reduced exposure to natural chicken pox will shift the timing of zoster toward a younger age group. Further, it remains unclear how long varicella immunity lasts following childhood vaccination, and one can develop zoster due to the strain present in the vaccine.
Another strategy that may work to counter the demonstrated lack of effectiveness of many vaccines in seniors is to use adjuvants that activate different toll-like receptors (TLRs). A number of these specifically targeted for different vaccines are under development. They could be delivered through methods such as an immunostimulant patch that can be laid over the top of the immunization site.
Obesity also plays a role in vaccine non-response, said Dr. High. Studies have found that obese adults—women with BMIs over 35 in particular—require very long, 32 mm needles for vaccines that must be injected into muscle below a thick subcutaneous fat layer in order to receive the proper dose of vaccine.
Finally, a major challenge for the health care community is increasing the vaccination rates of older adults, which historically have been low, said Dr. High. "If you don't give the vaccine, there is no chance the patient will get an immune response."
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