Despite the national shortage, vaccination prevalence remained high among users of outpatient VHA facilities aged ≥65. This finding is consistent with prior studies of influenza vaccination among veterans and VA users.8
VHA has many organizational features that influence influenza vaccination delivery including the system-wide use of electronic clinical reminders, an influenza vaccination performance measure with facility-level feedback, and national flu and infection control campaigns that include facility-level toolkits to increase staff and patient awareness of influenza prevention. Additional actions during the 2004–2005 season may have helped sustain high vaccination rates, which included a requirement that systems be in place to call back VHA patients deferred from vaccination because of initial shortages and clearly defining “direct patient care” health care providers to help preserve vaccine supply for patients.
Our findings suggest that VHA users between ages 50 and 64 were most affected by the national shortage as indicated by decreased influenza vaccination prevalence in this age group compared to previous years. Furthermore, among the unvaccinated we found a strong association with citing the “told not eligible” reason for the age group 50–64 as compared to the age group ≥65. VHA redistributed vaccine within its own system, a measure we viewed as largely successful because VISN (the administrative unit by which redistribution occurred) was not strongly associated with either vaccine receipt or with citing a shortage-related reason for not getting vaccinated.
Similar to our results, the decline in vaccination nationally was smallest for adults aged ≥65 and larger for younger age groups. Data from the CDC’s Behavioral Risk Factor Surveillance System found that vaccination prevalence for respondents ≥65 years decreased from 67.6% to 63.3% between 2004 and 2005.9
Vaccination for adults in nonpriority groups declined by about half and experts attribute this to approximately 17.5 million adults who cited wanting to save vaccine for those who needed it more as the reason for not being vaccinated.10
The National Committee for Quality Assurance analyzed data from commercial managed care plans and found vaccination prevalence among those aged 50–64 declined by nearly half from 52.4% in 2003–2004 to 28.1% in 2004–2005.11
In this study, older patients and those who reported poorer health status experienced smaller relative decreases between seasons compared to younger patients or those reporting excellent or good health.
In our study, shortage-related reasons were among the most frequently cited reasons reported for not getting vaccinated in patients of both age groups. Unfortunately, these reasons were not available as item responses on the SHEP survey before 2004–2005 limiting direct comparison to earlier years. Vaccine unavailability first appeared in 2000–2001 as 1 of the leading reasons for nonvaccination in the Medicare Current Beneficiary Survey with nearly 12.7% of respondents reporting vaccine unavailability.12
Santibanez et al.13
reported no change in the overall vaccination rate in 1 large metropolitan area after a vaccine shortage in 2000; however, these investigators did find that subjects who were patients of practices who received their vaccine late in the season were more likely to report a source of vaccination other than their regular doctor. These findings all suggest that even further gains in vaccination both within and outside of VHA could be achieved by simply ensuring that a timely and adequate vaccine supply is available.
VHA was able to use its position as a national health care system to advantage in managing the shortage. On announcement of the shortage, VHA leadership immediately entered discussions with Aventis Pasteur, Inc. to confirm that its contracted vaccine supply would be delivered and with CDC to ensure recognition of VHA as the source of vaccine for a sizable number of persons in high-priority groups. VHA communicated information on vaccine supply, distribution, nonvaccine preventive measures and policies on prioritization frequently throughout the season to its VISN leaders and facility staff via a series of 7 nationally electronically mailed advisories from the VHA executive, the Under Secretary for Health.14
VHA assessed its vaccine supplies within VISNs in mid-December 2004, mid-February 2005, and early April 2005 to redistribute between VISNs and to prepare for possible redistribution of any unused VHA-owned vaccine outside the VHA system. When it became clear by late January that redistribution outside VHA would not be needed, VHA encouraged “late season” vaccination within its health care system, an action that resulted in over 17% of its supply being administered after the middle of December, the traditional end of influenza vaccination in most years. By April 6th, only 9% of the 2.1 million doses received remained unused.
One of the unanticipated benefits of the national shortage for VHA was the establishment of a mechanism for providing timely updates to VHA staff in the field via the use of “Flu Advisory” emails and web postings. Non-vaccine preventive measures were emphasized with the initiation of a hand-washing and respiratory-hygiene promotional campaign within VHA called Infection: Don’t Pass It On
, which has evolved into an ongoing effort.15
VHA can build upon this infrastructure in emergency preparedness planning for future public health emergencies such as pandemic influenza, bioterrorist emergencies, and other urgent national public health threats.
This study has several strengths. First, we used SHEP data, a survey with a good response rate collected from a large, geographically representative sample of VHA outpatients. The survey items used to assess reasons for not getting vaccinated included items specifically related to a vaccine shortage. Lastly, historical vaccination prevalence from similarly designed and conducted SHEP surveys was available for comparison.
Our study has several limitations. We lacked information based on VHA administrative data to determine the degree of bias owing to SHEP survey nonresponse. However, nonresponse weights based on the available demographics were applied to minimize this bias. The use of self-reported vaccination status is also a limitation; however, previous studies have confirmed reliability of self-reported influenza vaccination.16–18
We did not have information on medical comorbidities of respondents. This would have been helpful for patients aged 50–64 because this information would better characterize eligibility for vaccination. Finally, the large sample size in our study may have yielded statistically significant results with little or no clinical significance.
We are limited in drawing definitive conclusions about specific supply and demand forces at play during the 2004–2005 influenza season. Our estimates were derived from a survey sample; we do not know the absolute numbers of patients that were vaccinated. Because some of the VHA vaccine supply is used to vaccinate employees, we are unable to estimate the absolute numbers of vaccinated patients based on vaccine supply that was used. Furthermore, we have no information on the absolute numbers of patients who sought vaccination but were turned down because of the shortage. Because of changes in the item used to determine vaccination setting between 2002–2003 and 2003–2004, we are not able to draw conclusions based on changes in vaccination source. These data would have better characterized the supply and demand forces.