Research article
Improving Influenza Vaccination Rates in the Workplace: A Randomized Trial

https://doi.org/10.1016/j.amepre.2009.11.011Get rights and content

Background

To minimize absenteeism resulting from influenza, employers frequently offer on-site influenza vaccination to employees. Yet the level of uptake of vaccine is low among working adults. This study was designed to increase workplace influenza vaccination rates by offering both a choice of intranasal (LAIV) and injectable (TIV) influenza vaccines to eligible employees, and an incentive for being vaccinated, and by increasing awareness of the vaccine clinic.

Design

This study used a stratified randomized cluster trial.

Setting/participants

A total of 12,222 employees in 53 U.S. companies with previous influenza vaccine clinics were examined.

Interventions

Control sites advertised and offered vaccine clinics as previously done. Choice sites offered LAIV or TIV and maintained their previous advertising level but promoted the choice of vaccines. Choice Plus sites increased advertising and promoted and offered a choice of vaccines and a nominal incentive.

Main outcome measures

These included vaccination rates among eligible employees. Hierarchic linear modeling (HLM) was used to determine factors associated with vaccination.

Results

The overall vaccination rate increased from 39% in 2007–2008 to 46% in 2008–2009 (p<0.001). The difference in vaccination rates for LAIV was 6.5% for Choice versus Control and 9.9% for Choice Plus versus Control (both p<0.001). Rates of TIV increased by 15.9 percentage points in the Choice Plus arm versus Control for workers aged ≥50 years (p=0.024). Rates of TIV did not change in workers aged 18–49 years in either intervention arm or in workers aged ≥50 years in the Choice arm. In HLM analyses, factors significantly associated with increased vaccination were older age, female gender, previous company vaccination rate, and the Choice Plus intervention.

Conclusions

An incentive for vaccination, an intensified advertising campaign, and offering a choice of influenza vaccines improved vaccination rates in the workplace.

Introduction

Influenza is the most commonly occurring vaccine-preventable disease, resulting in an estimated 226,000 excess hospitalizations and 36,000 deaths in the U.S. annually.1 Although most influenza-related morbidity and mortality occurs among the very young and very old, all age groups are affected, including the working population. More than one half of the 216.5 million U.S. adults aged 20–64 years are employed,2 making working adults the largest group affected by influenza.3 Those infected may become debilitated, bedridden, miss up to 6 days of work per infection, and require up to 2 weeks for full recovery.3 Influenza has been estimated to cause more than 70 million lost working days in the U.S. each year4 and to result in $16.3 billion in lost earnings.5

Among adults, influenza vaccine is recommended for those with chronic health conditions, all those aged ≥50 years, caregivers of young children and older adults, healthcare workers, and anyone who wishes to prevent influenza disease, among others. The workplace is the most common location to receive an influenza vaccine outside the physician's office, with a reported one third of vaccinees aged 18–49 years and one fifth of vaccinees aged 50–64 years receiving the vaccine at work.6 For these reasons, the worksite is an ideal place to vaccinate large numbers of eligible individuals against influenza. A 2004 survey7 found that 70% of U.S. corporations offer influenza vaccines in the employer setting. Unfortunately, workplace vaccination rates are low even among employees who are afforded the convenience of on-site vaccination, often without charge. One study8 reported that 18% of nearly 1000 U.S. companies vaccinated more than 50% of their employees. In a recent survey9 of 54 U.S. corporations, 96% of which employed >1000 full-time workers, only eight (15%) reported on-site influenza vaccination rates that were higher than 50%. Even among healthcare personnel, whose vaccination against influenza is a patient safety issue,10, 11, 12 the average national vaccination rate is only 42%.1

As reported in studies13, 14, 15, 16, 17, 18, 19, 20, 21, 22 of healthcare workers, working adults, and adults with unreported working status, reasons for not receiving the influenza vaccine include respondents' belief that healthy people do not need to be vaccinated, lack of physician recommendation, fear of vaccine side effects, infrequent physician visits, and aversion to needles. Conversely, improved access to vaccine and elimination of cost have been shown to be inducements to influenza vaccination;15, 23 both of these factors are addressed by on-site, free vaccine clinics. Previous influenza vaccination is a powerful predictor of vaccine uptake,22, 24 as is an individual's estimate of the percentage of coworkers who are accepting vaccination.22 Therefore, a program designed to increase overall workplace influenza vaccination rates would (1) inform working adults about influenza vaccination recommendations and advertise the availability of an on-site influenza vaccine clinic; (2) reduce barriers such as fear of side effects, cost, and inconvenience; and (3) help establish the habit of receiving influenza vaccine.

The purpose of this study was to improve workplace influenza vaccination rates overall and among workers aged <50 years, by increasing advertisement efforts to heighten awareness of the vaccine clinic; promoting influenza vaccine clinics with a choice of vaccine type (i.e., injectable trivalent inactivated influenza vaccine [TIV] or intranasal, live attenuated influenza vaccine [LAIV, MedImmune]) to minimize needle aversion; and offering employees an incentive for receiving vaccine to encourage first-time vaccinees.

Section snippets

Site Selection, Inclusion, and Exclusion Criteria

Passport Health, Inc. (PHI), a travel vaccine company that provides employer-based influenza vaccine clinics across the U.S., developed a list of potential employers estimated to have ≥60 employees that contracted with them for employee influenza vaccine clinics during the past three influenza seasons. These employers were contacted by the local PHI office to determine their interest in participating in the study. Participating sites were offered an influenza vaccine clinic on site at no cost

Results

Of the 131 companies contacted by PHI, 44 (33.6%) refused to participate or did not respond. Of the remaining 87 sites, 33 did not meet the basic eligibility criteria; therefore, the remaining 54 were randomized (Figure 1). Of the companies excluded, only one site was excluded for having used seven doses of LAIV in the past season; there were only two screened employers that recorded any LAIV use.

The overall 2007–2008 vaccination rate for all employees among the ineligible sites was 34.2±15.2%

Discussion

Lost work time resulting from illness of workers or their family members leads to considerable productivity losses in business and industry. Hence, businesses have integrated health and wellness programs, such as exercise and nutrition classes, smoking-cessation programs, and psychological counseling, on site to provide workers convenient access, to reduce disease burden, and to lower health insurance premiums. One such employee wellness program is annual influenza vaccination. Workplace

Conclusion

A national randomized cluster trial found a modest increase in the uptake of influenza vaccine among employees offered on-site vaccination clinics. An incentive for vaccination, an intensified advertising campaign, and offering a choice of influenza vaccines improved vaccination rates in the workplace and can be used across a variety of non-healthcare business types and sizes.

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