DOD Flu Vaccinations: A Fight for Readiness 3
DOD Flu Vaccinations: A Fight for Readiness
Major Marc Skinner
Captain Marie Hoffman
Captain Michael McLain
Captain Greg Taylor
Army/Baylor Class of 2016
Executive Summary
This paper outlines research on the effectiveness of the influenza vaccination on various demographics and through diverse methods of administering the vaccine. Included in this analysis are the overall impact of herd immunity on a military population and the determination of a necessary population percentage for preventing the spread of influenza. Suggestions for additional research are provided along with real-world patient data pulls from specified locations which indicate a correlation between herd immunity in isolated populations and lower incident rates of the flu. Recommended improvements include the consideration of patient demographics for administering vaccinations. This will assist in improving processes by cutting DoD costs and improving the overall incident rate of influenza.
Keywords: vaccinations, influenza, herd immunity, military, readiness
DOD Flu Vaccinations: A Fight for Readiness
The practice of compulsory flu inoculation of military members, and strong encouragement of military family members, is considered a necessary process for maintaining a ready fighting force. Although research supports the potential for decreased influenza incidents by means of vaccination, the question must be asked: can the process be improved? This essay will include a brief analysis of the effectiveness of various flu vaccination methods on specified patient demographics as well as and the impact of herd immunity within the Military Health System (MHS). The overall objective of this paper is to discover improvements to the Department of Defense (DoD) vaccination process and to demonstrate a set herd immunity percentage among relatively homogeneous populations through real-world patient data.
Background/Literature Review
A total of 32 research articles were reviewed, seven of which are included within the literature review. This section is broken into two separate research categories: vaccinations and herd immunity. Although the two categories are not mutually exclusive, the title heads indicate the focus of research within each section.
Vaccinations
Influenza is a viral condition that most commonly affects the respiratory tract. Every year, on average, 5% to 20% of the U.S. population contracts the flu (“seasonal influenza”), in which more than 200,000 people are hospitalized (Centers for Disease Control and Prevention, 2014). Flu rates across the armed forces varies from year-to-year, with one study reporting that 10.6% of basic trainees contracted the flu, including five individuals who were immunized (Russell, et al., 2005), while another reported a range of 7.8% up to 19.4%, depending on immunization status (Wang, Tobler, Roayaei, & Eick, 2009). Influenza has a direct negative impact to a critical component of the military’s quadruple aims: readiness.
The influenza vaccination has been used by the armed forces since World War II to prevent severe losses to unit readiness (Grabenstein, Pittman, Greenwood, & Engler, 2006), despite lacking empirical evidence demonstrating the efficacy or effectiveness of immunization (Osterholm, Kelley, Sommer, & Belongia, 2012). In a recently published Cochrane Review, experts estimated that influenza vaccination saves 0.04 working days per worker, on average, due to influenza (Demicheli, et al., 2014). Influenza vaccinations are either inactivated (administered intramuscularly) or live, attenuated (administered intranasally). Each method has been shown to have different efficacy and effectiveness when age and prior immunization status are controlled.
In a review investigating the effectiveness of inactivated influenza vaccinations, the authors reported that vaccination was 16% effective in preventing influenza-like illness symptoms when strains in the vaccine matched those in circulation (Demicheli, et al., 2014). The authors of the same review reported the effectiveness of the live, attenuated influenza vaccine as 10% (Demicheli, et al., 2014), with or without antigen matching. In a study investigating influenza vaccinations effects in the military, those members younger than 25 years had an effectiveness of 50% (Johns, et al., 2010). Surprisingly, those service members in the age group of 25-29 had an effectiveness of -6%, compared to the 30-39 year olds with only 9% effectiveness (Johns, et al., 2010). Wang reported a superior effectiveness among military personnel when the inactivated virus method was used for vaccination (2009); a surprising result since military personnel are consistently encouraged to receive the live virus.[1]
Herd Immunity
The concept of herd immunity describes the degree of protection from infectious diseases conferred to the non-immunized due to lack of a host organism in the population (the “herd”). This concept has not been well studied among military members. One study reported zero episodes of influenza in a community where 84% of the population had been immunized (Warburton, Jacobs, Langsford, & White, 1972), and yet another suggested an immunization rate of 78% (Cohen, Brezis, Block, Diederich, & Chinitz, 2013).
The military medical database (M2) was queried, comparing military populations in a rural location (Ellsworth Air Force Base, Rapid City, SD) to that in an urban location (Nellis Air Force Base, Las Vegas, NV). The assumption was that the population in Rapid City was predominantly military compared to a largely transient, heterogeneous population, giving a reasonable approximation to confer herd immunity against seasonal influenza. The objective of this analysis is to capture the effects of herd immunity on the incidence rate (per 1,000 military members) of influenza.
The data does in fact demonstrate a higher incidence rate among the urban site compared to that of the rural community. Since 2010, the urban site averaged a rate of 39.27 compared to the rural rate of 22.95. While this data cannot attribute singular causation, it indicates the influence that herd immunity has in reducing the incidence rates of flu among military members.
Results/Implementation Methods
Studies have demonstrated a wide range of conclusions regarding the efficacy of flu vaccinations and their ability to maintain a fit and ready fighting force. The process by which a vaccine is administered, the virus strand type, and the age of the patient have demonstrated diverse efficacies. Although studies have shown significant impact to younger military members, the overall effect on work absenteeism is a mere 0.04 working days on average (Demicheli, et al., 2014). As such, the question must be asked: can the process be improved?
With vaccination effectiveness ranging from 50% to -6% based on age, it is evident that specific demographics have the potential to alter the overall effectiveness of flu vaccinations (Johns, et al., 2010). However, further research is necessary to further delineate the effective age ranges for vaccination as well as the impact of live and inactivated viruses on those specified age ranges. By varying vaccination methods to match specific age ranges, there is potential to immediately lower the overall incident rates of influenza among military members[2] and reduce the cost for unnecessary vaccinations. Such costs currently have the appearance of cost avoidance by the DoD, especially since military members do not pay a co-pay, however this can nonetheless be reduced by upwards of $0.70/person[3] in direct costs simply by cutting vaccinations for age ranges which typically are less vulnerable to infection. Significant evidence implies vaccinations for soldiers less than 25 years of age would be the most cost effective and provide the greatest benefit per vaccination (Johns, et al., 2010).
Additionally, healthcare workers who will have consistent exposure to the virus (due to un-vaccinated patients) should consider the use of the inactivated vaccine. This process will reduce the potential for infection due to higher immunity success rates with this vaccine type (Wang, Tobler, Roayaei, & Eick, 2009). This data, however, misses the concept and importance of herd immunity and readiness among a military community; one of overall goals for the MHS[4].
There is a lack of current research on herd immunity within a military community and its impact on the incidence rate. Although studies report ranges from 78% (Warburton, 1972) to 84% (Cohen, 2013), having a more accurate percentage range that can be adapted to the unique requirements of a community will give healthcare works a target for increasing the possibility for herd immunity. Queried M2 data suggests correlation between the concept of herd immunity among a relatively isolated military population and a lower flu incidence rate. Although causation cannot be determined from this data set and more research should be conducted, the extreme disparity of incident rates among relatively homogeneous populations must be recognized. Herd immunity can, at the very least, improve the potential for vaccination success.
Conclusion
The overarching goal of military readiness is paramount to mission success; much of which includes health and the ability to stem the spread of infectious disease. By improving processes to affect an overall population of military members, and by seeking to use tailored outcomes-based procedures for administering vaccinations, the military can effectively cut costs, improve upon current processes, and overall readiness. The herd immunity concept must be considered when implementing these procedures in light of increased incident rates due to diverse (and un-immunized) communities[5]. It is paramount that procedures remain flexible to allow for the inclusion of further research. Once trial sites demonstrate decreased influenza incidence rates due to modification to their vaccination process, processes can be replicated throughout the DoD. Sustainability will depend on the DoD’s adaptation and anticipation to new strains of influenza; flexibility is the key. The innovation of applying evidence-based changes and tailored outreach to said processes is demonstrated through monetary savings and the increased readiness of our military members.
DOD Flu Vaccinations: A Fight for Readiness 3
References
Centers for Disease Control and Prevention. (2014, August 14). Seasonal Influenza Q&A. Retrieved from CDC.gov: http://www.cdc.gov/flu/about/qa/disease.htm
Cohen, M. J., Brezis, M., Block, C., Diederich, A., & Chinitz, D. (2013). Vaccination, Herd Behavior, and Herd Immunity. Sage Journals.
Demicheli, V., Jefferson, T., Al-Ansary, L. A., Ferroni, E., Rivetti, A., & Di Pietrantonj, C. (2014). Vaccines for preventing influenza in health adults. Cochrane Database of Systematic Reviews(3), 1-267. doi:10.1002/14651858.CD001269.pub5
Grabenstein, J. D., Pittman, P. R., Greenwood, J. T., & Engler, R. J. (2006). Immunization to protect the US armed forces: heritage, current practice, and prospects. Epidemiologic Reviews, 28, 3-26. doi:10.1093/epirev/mxj003
Johns, M. C., Eick, A. A., Blazes, D. L., Lee, S., Perdue, C. L., Lipnick, R., . . . Sanchez, J. L. (2010). Seasonal influenza vaccine and protection against pandemic (H1N1) 2009-associated illness among US military personnel. PLoS ONE, 5(5), e10722. doi:10.1371/journal.pone.0010722
Osterholm, M. T., Kelley, N. S., Sommer, A., & Belongia, E. A. (2012). Efficacy and effectiveness of influenza vaccines: a systematic review and meta-analysis. Lancet Infect Dis, 12, 36-44. doi:10.1016/S1473-3099(11)70295-X
Russell, K. L., Ryan, M. A., Hawksworth, A., Freed, N. E., Irvine, M., & Daum, L. T. (2005). Effectiveness of the 2003-04 influenza vaccine among U.S. military basic trainees: a year of suboptimal match between vaccine and circulating strain. Vaccine, 23(16), 1981-1985.
Wang, Z., Tobler, S., Roayaei, J., & Eick, A. (2009). Live attenuated or inactivated influenza vaccines and medical encounters for respiratory illnesses among US military personnel. JAMA, 301(9), 945-953.
Warburton, M. F., Jacobs, D. S., Langsford, W. A., & White, G. E. (1972). Herd immunity following subunit influenza vaccine administration. Med J Aust, 2, 67-70.
[1] Based on personal experiences; empirical data is not supplied to support this theory.
[2] Johns (2010) suggests that the 25-29 age range has a negative effective rate to the flu vaccination, cutting the vaccination would result in an immediate improvement to the overall rate.
[3] Per-person cost calculated from 2013 Influenza vaccination supply purchase at Dover AFB.
[4] Based on the MHS “quadruple aim”, and the element of readiness.
[5] Cutting the 25-29 age range (Johns, 2010), which was shown to have negative results from immunization, may not individually benefit from the vaccine, however eliminating them from the population would skew the percentage for herd immunity. This affect must be considered.