High-dose Influenza Vaccine Reduces Hospitalizations among Nursing Home Residents
by Lynn Hetzler
Results of a new study show that high-dose influenza vaccine could lead to fewer hospitalizations among nursing home residents.
Influenza is a major cause of serious illness and death among older adults, particularly among residents of nursing homes. Influenza infections can lead to lower respiratory tract infections, including pneumonia, bronchitis and tracheobronchitis, severe enough to warrant hospitalization. These infections can also increase mortality in older adults, particularly those frail residents of nursing homes.
Pneumonia and influenza are the fifth leading cause of death in older adults in the United States, according to the Centers for Medicare and Medicaid Services. To help reduce influenza transmission among nursing home residents, the CMS began requiring that nursing homes participating in the Medicare and Medicaid programs ensure their residents receive vaccinations for influenza and pneumococcal pneumonia in October of 2005. To help cover costs, Medicare pays for one seasonal influenza immunization each influenza season for all beneficiaries.
Between 71 and 85 percent of seasonal flu deaths occur in people age 65 and older, according to the Centers for Disease Control and Prevention, and between 54 and 70 percent of hospitalizations due to seasonal flu occur in this age group. Vaccinations can help reduce the risk of influenza infections.
High vaccination rates among nursing home residents and staff reduce transmission rates of the influenza virus. Vaccination can also significantly decrease hospitalization, pneumonia and related mortality, according to American Family Physician.
Reducing influenza infections is particularly important in nursing homes. Because of their age and comorbid conditions, residents there are at special risk for complications of influenza. Mortality rates can exceed 5 percent among nursing home residents during influenza outbreaks. The communal living environment makes transmission between residents more likely. Nursing staff, visiting friends and family members, volunteers, and other visitors increase the risk of exposure to the flu virus.
Unfortunately, vaccines do not work as well in older people.
Vaccinations work by introducing an antigen, which prompts an immune response that protects the body from subsequent viral infections. Older adults, particularly those with weakened immune systems, have a lower protective immune response to vaccination – their bodies do not respond adequately enough to build immunity to the viruses.
The new study, published in Lancet Respiratory Medicine, suggests quadrupling the dose of antigen to compensate.
Previous research showed that older adults responded better to high-dose vaccines, but that study involved older participants in good health. This newer study investigated whether high-dose vaccines would benefit older adults who are in poor health, like those who reside in nursing homes.
High-dose vaccinations work better in at-risk population
“In our study, a quarter of the sample was over 90. So we asked if the high-dose vaccine also would work better than regular-dose vaccine in the population we consider least able to respond. This paper says yes, it can,” said lead author Dr. Stefan Gravenstein, a professor at the School of Public Health at Brown University and at Warren Alpert Medical School. Gravenstein is an adjunct professor of medicine at Case Western Reserve University and is also affiliated with the Providence Veterans Affairs Medical Center.
In this study, researchers used Medicare claims data gathered during the 2013-2014 flu season to compare hospitalization rates among more than 38,000 residents of 823 nursing homes across 38 states. Nearly half of the nursing homes – 409 facilities – administered the high-dose vaccine. Health professionals in the other 414 nursing homes administered the standard dose.
Over the six months following vaccination, hospitalization rates for respiratory illnesses were 3.4 percent among the high-dose residents while hospitalization rates were 3.8 percent for those receiving the standard dose. The researchers reported a 12.7 percent reduction in hospitalizations for pneumonia and other respiratory illnesses and an 8.5 percent overall reduction in hospitalizations among participants who received the high-dose vaccinations.
The researchers also found that the rate of hospitalization for any reason was significantly lower in the high-dose group of residents. For every 69 people receiving high-dose vaccine rather than standard-dose vaccine, one more individual avoided hospital admission during the flu season. The stronger vaccine appeared to help prevent cardiovascular symptoms and other problems that might have otherwise led to hospitalization.
“Respiratory illness as the primary reason for hospitalization accounted for only about a third of the reduction in hospitalization that we measured,” said Gravenstein.
This significant reduction in hospitalizations is notable because health experts believed the predominant flu strain that season, A/H1N1pdm, was less potent in older adults who had built up immunity to other strains over the course of their lifetimes.
“That there was differential protection in this context both underlines the potential importance of even low-virulence or less transmissible strains to older populations and the fact that vaccines may afford relevant effectiveness among frail older persons even when A/H1N1 predominates,” the authors add.
The study found no significant difference in the rate of death, however. The authors speculate that while the standard-dose vaccine may have been too weak to prevent illness entirely, it may have been strong enough to prevent deaths when used in combination with hospital care. While high-dose vaccines did not reduce rates of death and are more expensive than standard-dose vaccines, the significant reduction in hospitalizations is still beneficial to nursing home residents. This is especially true for older, frail patients, as reducing trips to the hospital helps residents maintain a higher quality of life.
The manufacturer of the high-dose vaccine, Sanofi Pasteur, supplied the vaccine and provided funding for the study. The authors of the study said that the company did not participate in the design of the study, nor was it involved in the collection, analysis or interpretation of the data.