Mumps is an acute viral illness that usually presents with swelling of the parotid or other salivary gland(s); up to one-third of infections can be asymptomatic in an unvaccinated population. (1, 2). Mumps is vaccine preventable. In 1977, the United States (U.S.) Advisory Committee on Immunization Practices (ACIP) recommended one dose of mumps vaccine for all children at any age after 12 months (1). In 1989, children began receiving two doses of mumps vaccine after implementation of the two-dose measles ACIP vaccination policy using the combined measles, mumps, and rubella (MMR) vaccine (1, 3). After the vaccine recommendations were enacted, reported mumps cases fell more than 99% in the U.S. accompanied by substantial savings in healthcare costs (4, 5). The mumps component of the MMR vaccine is 78% effective after one dose (range: 49%−92%) and 88% effective (range: 31%–95%) after two doses (1, 6).

Since 2012, an increase in mumps cases and outbreaks has been reported to the Centers for Disease Control and Prevention (CDC), primarily associated with college settings (7, 8). These outbreaks ranged in size from three to several hundred cases, mostly affecting young adults, and are likely the result of a combination of factors, including <90% vaccine effectiveness and waning of vaccine-induced immunity over time, lack of exposure to wild-type virus, and close contact that leads to increased risk for exposure coupled with behaviors that increase the risk for transmission (9). There is insufficient publicly available documentation of the cost of these outbreaks and only one recently published study on the cost of a mumps outbreak in a college setting (10).

On February 8, 2017, a suspected case of mumps in a member of a sorority at the University of Washington’s (UW) Seattle campus was reported to Public Health—Seattle & King County (PHSKC). By June 6, 2017, 42 mumps cases were identified among UW students (primarily sorority and fraternity members), staff, and associated community members (11); no hospitalizations or deaths occurred. In a university-wide effort, UW collaborated with PHSKC and Washington State Department of Health (WADOH) to rapidly respond to and contain the outbreak. The UW outbreak occurred amid Washington State’s largest mumps outbreak in 40 years, although the two outbreaks were unrelated (different virus lineages in specimens tested) (11–14). This study reports the economic impact of the 2017 UW mumps outbreak on UW and the state and local health departments.

Total costs incurred responding to the 2017 UW Mumps Outbreak were $282,762 (or $6,732 per case), including material costs and 2,692 hours of labor accrued. UW spent $160,664 ($3,825 per case), including material costs and 1,495 logged hours and overall PH costs were $122,098 ($2,907 per case), including material costs and 1,197 logged hours (Table 1). The number of contacts was not available to compute cost per contact. However, if sorority and fraternity population were to be used as a proxy, the total cost per contact would be $61/contact.

Comparing outbreak containment versus vaccination-related activities, containment-related hours and labor costs were three-fold higher than vaccination-related activities (Table 2). PH spent $75,295 (957 hours of labor) on containment-related costs and $23,472 (240 hours of labor) on vaccination-related costs. UW spent $91,507 (1096 hours of labor) on containment-related costs and $26,483 (400 hours of labor) on vaccination-related costs. Adding material costs of laboratory testing and vaccination (vaccines and vaccine supplies) to the labor costs increases PH’s total by 24% (from $98,767 to $122,098) and UW’s costs by 36% (from $117,990 to $160,664) (Table 1). Examining the material cost of the MMR vaccine doses alone, PH paid for 406 doses costing $13,058 at CDC contract vaccine prices (246 adult at $40.00 per dose and 160 child doses at $20.11 per dose), while UW purchased 581 doses costing $40,424 ($69.58 per dose) at private party vaccine prices (all adult doses) (Table 1) (19).

We then examined the seven subcategories of containment and vaccination-related labor activities: communication; case and contact investigation; response planning and coordination; preparing reports; laboratory testing; vaccination clinic planning; and vaccination clinic operations (Table 2). PH and UW accrued almost identical communication costs (including education and media); approximately $11,000 each, although UW incurred almost twice the number of hours on this subcategory. PH case and contact investigation costs ($24,256) represented 25% of their total labor costs. UW case and contact investigation costs ($3,377) were 3% of their total labor costs. PH response planning and coordination costs accounted for only 19% of their total labor costs, but UW response planning and coordination costs accounted for 64% ($75,493) of UW total labor costs. PH laboratory testing costs of $20,445 were 21% of their total labor costs. UW did not incur laboratory costs or hours. Vaccination clinic planning costs accounted for 13% of PH total labor costs and 19% of UW total labor costs. PH incurred $11,039 administering the vaccination clinics, 11% of PH total labor costs. UW incurred $3,870 administering the vaccination clinics, 3% of UW total labor costs.

Overall, labor accounted for 77% of total outbreak costs (Table 1). The majority of labor costs were incurred containing the outbreak (77%) (Table 2).

During February 8–June 6, 2017, 42 mumps cases were identified among UW students, staff, and associated community members. UW and PH incurred costs totaling >$282,000 and spent almost 2,700 hours responding to and containing the outbreak. Overall, labor was the largest driver of costs in this outbreak accounting for more than three-fourths of the total outbreak costs.

Examining the distribution of hours spent responding to the 2017 UW mumps outbreak between UW and PH, we found that UW and PH incurred roughly equal hours and costs. UW spent more hours for: (1) planning how to respond to the outbreak, (2) preparing for the vaccination clinics, and (3) outreach and education campaign. Many of these hours can be attributed to addressing the legal, medical, and administrative aspects of developing a contract for an additional mass third MMR dose vaccination clinic, including the nuances of an off-label use, which did not occur as the outbreak ended. These hours also might be a result of UW’s limited experience with mumps or other infectious disease outbreaks, which is likely true for most universities in the U.S. Universities with a history of prior outbreak response might not incur a portion of the costs required to respond to the current outbreak (i.e., sunk costs). For example, a university with a recent measles or meningitis outbreak might not have mumps experience, but might know the most effective mode of outreach to students (e.g., telephone calls or emails) and thus, might put less effort into other outreach efforts. If UW were to experience another outbreak of mumps or communicable disease, they would be able to benefit from lessons learned during this outbreak response. These lessons learned will assist in developing flexible protocols that will save some of the response costs associated with a future outbreak and serve as a reference for other universities.

UW found four key factors attributed to the successes in their response: a well-established relationship with PHSKC, strong collaboration across the UW units and departments involved in the outbreak control effort, a robust effort to provide communication and education to all UW community members, and effective overall project management. In anticipation of future outbreaks, UW plans to make improvements such as updating and strengthening UW’s Communicable Disease Outbreak Management, providing a response blueprint, using a centralized storage system of informational documents for all campus partners to ease access to the information and educational materials, and clearly define the relationship between the outbreak control strategy group and the ongoing UW Advisory Committee for Communicable Diseases. PHSKC determined (1) a pre-existing health emergency response administrative structure at the university integrating PHSKC was extremely important, (2) due to low student concern about preventing mumps illness, uptake of vaccine was less than anticipated, and (3) the necessity of making vaccination as convenient as possible for students. PHSKC also concluded that a well-established relationship with UW prior to the outbreak facilitated decision-making and implementation of outbreak control measures. Further, both regular weekly meetings between PHSKC and UW and the in-person outreach to the sororities and fraternities aided in information sharing during the outbreak. The context in which the UW mumps outbreak occurred is important to consider when evaluating the cost and hours spent. Washington State was in the midst of its largest mumps outbreak since the late 1970’s, accounting for 16% of mumps cases occurring nationally during January–September 2017 (13, 14, 20). Although the mumps cases at UW represented only 6% of the state’s total cases, PHSKC and WADOH allocated important resources to assist UW in responding to the outbreak while also responding to the larger Washington State outbreak. PHSKC conducted case/contact investigations and vaccination activities at UW and contributed to the outbreak response with epidemiologists, nurses, administrative professionals, program managers, and immunization managers. All of UW and PH involved staff diverted time from their regular duties to accommodate the outbreak response. Local health departments have been experiencing reductions in resources and do not have “outbreak” budget reserves, therefore, even relatively small outbreaks will likely represent real fiscal challenges (21).

Lastly, UW’s outbreak resulted in a relatively small number of cases. Although no direct causation can be drawn, the rapid response by UW and public health agencies and the robust amount of labor allocated to planning and coordination of the outreach and education campaign and vaccination clinics might have contributed to containment of the outbreak. UW’s spring break (March 20 – 24) and related student dispersal might have also contributed to curtailing the outbreak at the university. This analysis has several limitations. First, although the majority of costs were captured by UW staff participating in the response, not all participating staff tracked their time and were able to submit hours for this study. Further, no opportunity costs of staff diverted from primary work (or responding to the larger Washington outbreak) to this response were collected. Not including these costs underestimates the total cost and hours spent responding to the outbreak and thus the cost we report represent a lower bound of the total cost of the outbreak. Lastly, the cost of living is significantly higher in the Seattle area than other parts of the U.S. Higher wages likely contribute to a higher total cost.

Mumps outbreaks in highly 2-dose vaccinated populations have been increasing across the U.S., triggering discussion of outbreak prevention versus control strategies subject to the competing demands on public health agencies and affected institutions. As one strategy, in October 2017 ACIP recommended a third dose of MMR vaccine for individual protection for persons who are part of a group or population at increased risk for acquiring mumps as determined by public health authorities during an outbreak (6). Persons at increased risk might access vaccination through the routine vaccine delivery systems and a vaccination campaign is not required. At this time, evidence is limited and not sufficient to fully characterize the effect of a third dose of MMR vaccine on reducing the size or duration of an outbreak (6) and thus, prevention and control strategy discussions persist.

As demonstrated in this study, the costs to control a mumps outbreak can be significant for both public health programs and institutions affected. Although the outbreak was relatively small, the economic burden was large. The resources employed likely contributed to: (1) limiting the outbreak and the associated disruption to academic life and (2) possibly benefiting the university in terms of “sunk costs” for future outbreak responses.

Given the limited resources to respond to an outbreak, any discussion or economic analysis to determine optimal response strategies must take into account the cost of responding to an outbreak (as provided in this study), including opportunity costs for public health agencies and affected institutions responding to the outbreak, and identification of strategies to prevent these outbreaks (along with associated costs). The economic burden of the outbreak to UW and the public health authorities highlights the need for further scientific evidence on strategies to prevent or limit the size of outbreaks (such as vaccination versus only case/contact response) and their associated costs. The results from these studies can then be used to evaluate the cost-effectiveness of existing or new intervention strategies.

This study indicates (1) how the cost of responding to a mumps outbreak can burden an affected institution and public health department, (2) the importance of public health department planning for the cost of responding to even modest outbreaks, and (3) the importance of the economics component for future research in determining optimal response strategies to future mumps outbreaks.