But those rates are far from ideal, and they have remained flat for years. "Progress has been barely visible," Dr. Bruce Gellin, director of the National Vaccine Program at the U.S. Department of Health and Human Services, told Kaiser Health News. 

One of the reasons that adults in general may not bother getting shots is that vaccines for some of these commons ailments are not particularly effective, at least from the perspective of a consumer. The flu shot only reduces one's chance of getting the flu by 19 percent. But, as is the case with the shingles vaccine, doctors are emphasizing that shots can help reduce the severity of the sickness.  

But senior citizens may be even more reluctant to get elective immunizations because of the cost. While the Patient Protection and Affordable Care Act requires insurers to cover 100 percent of the cost of immunizations, Medicare beneficiaries are still forced to pay up to $100 in copayments for tetanus and shingles shots because they are covered by Medicare Part D, while shots for pneumonia and the flu are free under Medicare Part B.  

Perhaps because of the lack of demand, but also due to the short shelf life of tetanus and shingles vaccines and the complexity of billing private Medicare insurers, many doctors don't store the tetanus and shingles vaccines. Instead, they prescribe the vaccine to the patient, who can go get the shot at a pharmacy or clinic. It's an extra step that likely deters some from getting immunized.  

Health systems are developing ways to try to identify those who would most benefit from a vaccine. Finding those who haven't been immunized in recent years and contacting them is a start.