Societal Costs of a Measles Outbreak

Clark County is located south of King County (the most populated county in the state and where Seattle, WA is located) in the southwestern part of Washington State and shares a border with Oregon. The estimated 2018 population of Clark County, the fifth largest county in the state, was 481 857.⁸  Statewide vaccination coverage with 2 doses of measles-mumps-rubella vaccine among children enrolled in kindergarten during the 2018–2019 school year was 90.8% in Washington and 93.0% in Oregon, compared to the national average of 94%.⁹  In Clark County, at the end of 2018, 81% of 1- to 5-year-olds had received 1 dose of the measles-mumps-rubella vaccine, and 78% of 6- to 18-year-olds had received 2 doses (Washington State Immunization Information System).¹⁰  All children born in Washington are entered into the system at the time of birth. Health care providers report voluntarily into the system. Currently, >94% of public sites that participate in the Vaccines for Children program share data with the Immunization Information System.¹¹ 

From late December to April 2019, 71 patients with confirmed measles were reported in Clark County. Among these patients, 52 (73%) were <10 years old, and 61 (86%) were unvaccinated.¹  The 1 patient reported in King County was a 52-year-old adult with an unknown vaccination status.

CCPH’s Incident Management Team was activated on January 15, 2019. Suspected measles cases were investigated through patient interviews, electronic–medical-records review, and consultation with health care providers. Possible exposure settings and contacts were identified, and the vaccination status of contacts was assessed through review of vaccination registries or vaccination cards.¹  Self-reporting was not considered sufficient for vaccination status ascertainment. A total of 4011 persons were identified and contacted from 46 known exposures at numerous locations that included Clark County health care facilities, workplaces, churches, schools, child care centers, social gatherings, and households. Of the 4011 contacts, 839 (20.8%) were considered to be potentially susceptible to measles (ie, lacked presumptive evidence of measles immunity) and were quarantined. Acceptable presumptive evidence of immunity to measles includes written documentation of age-appropriate vaccination, laboratory evidence of immunity, laboratory confirmation of disease, or birth before 1957. In King County, >100 contacts were identified and investigated from exposures in 1 household, 1 workplace, 2 health care facilities, and 2 schools.

Measles diagnostic testing (ie, detection of measles-specific immunoglobulin M [IgM] and/or measles virus [MV] RNA) took place at the WADOH (548 samples), CDC (52 samples), and Oregon Health Authority (OHA) laboratories (84 samples). A total of 42 cases were laboratory confirmed and 30 were epidemiologically linked to confirmed cases. Of the 42 laboratory-confirmed cases, 13 were reverse transcription polymerase chain reaction–positive, 3 were IgM-positive, and 26 were both reverse transcription polymerase chain reaction–positive and IgM-positive.

To estimate costs related to this outbreak from the societal perspective, 3 types of costs were collected or estimated: response (labor, material, and contracted costs incurred containing the outbreak), direct medical (third party or patient out-of-pocket costs incurred in the treatment of infected individuals), and productivity losses (costs incurred from lost productivity due to illness and home isolation, exposure and quarantine, or providing care to infected or quarantined family members). All costs were converted to 2019 first-quarter dollars. We defined the outbreak period starting December 31, 2018, when CCPH was notified of the first suspected case of measles, through April 26, 2019, 42 days (or 2 maximum incubation periods) after rash onset of the last reported case.

Response costs consist of containment and laboratory testing costs incurred while investigating and controlling the outbreak. These costs are divided into 2 subcategories: (1) labor, which includes the hours worked by staff from several public health agencies who conducted response activities, such as contact tracing, testing, and surveillance, and (2) materials and contracted services, which includes laboratory supplies related to testing, office supplies, and administrative services. These 2 subcategories were partially an extension of our data collection process, which largely consisted of administrative record summaries generated by the accounting or finance departments of each entity that participated in the outbreak response. Contracted costs included contracted labor, but this was listed as a lump sum material cost to the respective public health department. A detailed description of the methods used to estimate public health and volunteer time and wages is available in Part 1 of the Supplemental Information.

Time spent (hours) incurred by personnel responding to the outbreak, along with associated wages, were collected from the CCPH, WADOH, PHSKC, OHA, and CDC through each entity’s accounting or finance department or, for the CDC, individual time sheets. For the CCPH, this included volunteer personnel from other public health departments and the Medical Reserve Corps in Washington State, Idaho, and Oregon as well as unaffiliated personnel who volunteered during the response. Time spent (hours) incurred by laboratory personnel, along with associated wages, was collected only from WADOH, OHA, and CDC.

Material costs incurred responding to the outbreak include laboratory supplies and diagnostic tests, incident supplies (eg, computer hardware), contractual and/or temporary staff support (eg, interpreters and/or call center), shipping and mailing (largely measles information to exposed or potentially exposed persons), transportation, printing, communication services, and travel. These costs were collected from the CCPH, WADOH, PHSKC, OHA, and CDC through each entity’s accounting or finance department.

Direct medical costs are costs associated with outpatient visits, hospitalizations, health care laboratory tests, prescription drugs, and over-the-counter drugs paid by a third party or out-of-pocket. To estimate direct medical costs, we used measles-related outpatient visit and measles-related–hospitalization cost estimates previously reported.^12,13  These costs were extracted from claims databases and, thus, are the payments of actual reimbursements by insurers to providers and not billed charges to insurance companies or families. The reported cost ranged from $4032 to $46 060 per hospitalization and from $88 to $526 per outpatient visit. In our base analyses, we applied the midpoint of the range of outpatient costs to the 70 patients who had outpatient encounters and midpoint of the range of hospitalization costs to the 2 patients who were hospitalized during the Clark County outbreak.

Productivity losses are the “indirect” cost of forgone activities that are caused by disability, disease, injury of affected individuals, or premature death. These costs include lost paid employment and, also, the value of nonmarket activities such as unpaid household services (eg, informal caregiving).¹⁴  In this analysis, productivity losses included both lost employment pay and nonmarket production by age and sex. These losses were calculated for patients diagnosed with measles and for persons who were home quarantined because of an exposure and lack of presumptive evidence of immunity as well as for caregivers of patients diagnosed with measles or persons quarantined. Additional details on the methods used to compute productivity losses are in Supplemental Table 3.

For patients diagnosed with measles, we used previously reported estimates of time spent at home because of measles illness from a study that took place in the United Kingdom.¹⁵  Individuals with confirmed measles reported spending a mean of 9.6 days (95% confidence interval: 9.3–11.7) away from work or school because of illness. We converted annual productivity estimates by age and sex from Grosse et al¹⁶  to daily productivity estimates. For patients younger than the age of 15 years, we assumed zero productivity loss for the child with illness, but we calculated the productivity-loss estimate for caregiver time using combined-sex– and combined-age–specific estimates.

The CCPH recommends a 21-day quarantine period for exposed persons who lack presumptive evidence. Data on the exact length of quarantine as well as the age of those quarantined were available for 630 of 839 persons quarantined (productivity losses were not calculated if age or length of quarantine was not included in the data). To estimate the costs associated with quarantine, we computed daily age- and sex-stratified productivity estimates for persons ≥15 years of age from annual estimates in Grosse et al.¹⁶  Productivity losses of 82 children aged 10 to 14 years were assumed to be zero. For children aged ≤9 years (173 of 630 quarantined persons), we assumed a caregiver would be needed and productivity losses would be incurred for the caregiver, using combined-sex– and combined-age–specific estimates. We further assumed there would be a caregiver/child ratio of 1:3 because of the possibility that children within a single family would be quarantined at the same time and have the same caregiver.

Sensitivity analyses were performed by varying costs related to direct medical care, productivity losses due to illness, and productivity losses due to quarantine. We recalculated costs using the upper and lower bound of ranges for outpatient and hospitalization costs, the 95% lower and upper confidence interval bounds of school or work days missed, and varying caregiver to quarantined children ratios assumption from 1:2 and 1:4.

By using base case assumptions, the overall societal cost of the 2019 Clark County, Washington measles outbreak was estimated to be $3.4 million ($47 479 per case or $814 per contact; Table 1). The largest component of the overall societal cost was incurred as part of the public health response to the outbreak (∼$2.3 million), followed by productivity-losses costs (∼$1.0 million), followed by direct medical costs (∼$76 000).

A total of 451 personnel participated in the outbreak response, with the majority from the WADOH (260 personnel; Table 2). The CCPH had 84 personnel and 66 volunteers participating. A total of 33 845 hours were spent responding to the outbreak, with >17 000 hours and 13 500 hours accrued by the CCPH and WADOH, respectively. Hours of labor included efforts related to investigating ∼4100 contacts and processing close to 700 laboratory tests.

Labor costs comprised the majority of expenditures associated with responding to the outbreak (∼$1.9 million of the $2.3 million in response costs), and, among labor costs, containment costs totaled ∼$1.8 million. Labor costs changed over the course of the outbreak, peaking in February (Fig 1).

Response material costs were ∼$380 000; just over one-half of material costs were incurred by contractual and temporary staff support, such as administrative support, nurses, and interpreter services. The material costs of the laboratory testing of 684 specimens, which was incurred by WADOH, OHA, and CDC, was ∼$16 000 (Table 2).

Direct medical costs were estimated at $76 000 ($23 000 for 70 outpatient visits and nearly $53 000 for 2 hospitalized patients; Table 1).

Total productivity losses were estimated to be $1.0 million, primarily because of 548 individuals who were quarantined because they were exposed and lacked presumptive immunity in Clark County ($935 000). This includes productivity losses for 375 persons aged ≥15 years and the caregivers of 173 children aged ≤9 years. The productivity losses from missed work for the 72 patients (8 were aged ≥15 years and 64 were caregivers of patients aged ≤14 years) in both Clark County and King County were ∼$94 000 (Table 1).

The total cost of the outbreak varied from $3.3 million by using the lower bounds to $3.5 million by using the upper bounds of the inputs evaluated in the sensitivity analyses. The results are reported Supplemental Table 3.

The Clark County outbreak lasted ∼4 months and cost >$3 million from the societal perspective. This corresponds to a cost per case and per contact (a contact of an identified case) of >$47 000 and >$800, respectively. In a recent literature review of the available data on the cost of outbreak responses, researchers examining 10 studies and 11 estimates, focusing primarily on response costs and costs from the public health perspective (not capturing full societal costs), reported a median of $32 805 per case and $223 per contact.⁷  Our results add to the literature on the costs of measles outbreaks and emphasize the considerable resources needed to stop MV transmission.⁷  In addition to costs directly incurred by public health agencies in outbreak response, there are significant productivity losses to consider among ill individuals, unvaccinated persons who were quarantined because of exposure and lack of presumptive evidence of immunity, and the caregivers of ill and quarantined children. Finally, costs related to health care encounters and medical treatment are also steep. The highest annual number of US measles cases in over 25 years was reported in 2019, and a threefold increase in global cases was reported the first 3 months of 2019 compared to 2018. These increases in measles cases in the United States and globally underscore the need to more fully understand the societal cost of measles cases and outbreaks and economic consequences of undervaccination.^17,18 

Within response costs, 79% were containment-related labor costs, demonstrating the significant amount of time and resources needed to track and trace all case-patients and contacts for such a highly infectious disease. Our results highlight the need to invest in the capacity of local and state health departments as well as federal institutions to prepare for and respond to measles outbreaks and outbreaks of other vaccine-preventable diseases.^19–21  This may be particularly important in jurisdictions with known pockets of undervaccination.^2,22–25  A lack of or limited public health containment efforts could translate to exponentially higher direct medical costs and productivity losses. Of utmost importance is the need to identify the potentially numerous and dispersed pockets of undervaccination across the United States. Identifying and closing these gaps in immunity would reduce the size and duration of outbreaks.

This study has several limitations. First, these costs are limited to only societal costs related to cases within Washington State and do not include additional societal costs related to cases outside the state. Although the majority of response costs were provided directly from the participating institutions, some costs needed to be estimated by using reasonable assumptions and information from peer-reviewed literature. Volunteer staff included community volunteers and volunteers from the medical and health sectors, but the wages we used to value volunteer time was an average wage for the county and, so, likely an underestimate for any public health and medical professionals who served as volunteers. Collecting volunteer time from time logs has limitations. For example, in some cases, DOH or CDC volunteer hours may not have been attributed correctly to the affiliated agency. Labor costs were collected retrospectively and through public health finance departments, rather than directly from the participants during the response. It is possible that some hours spent on the response were not captured if they were not coded to the response in the public health agency’s financial administration system. In economic evaluations, there are often discrepancies in how costs are reported and in methods used for cost accounting (often because of a different original purpose of collecting the data) and may lead to incomplete reporting of costs in evaluations such as the current study.²⁶  The direct medical costs were derived from commercial insurance inpatient and outpatient claims data and were not the actual expenses incurred treating patients diagnosed with measles in this outbreak or what the patient paid. Certain cost items could not be ascertained and incorporated into our estimates; these items include specific types of direct medical costs, such as over-the-counter drug expenses and out-of-pocket medical costs, and direct nonmedical costs, such as travel costs incurred by seeking care. Furthermore, no opportunity costs of public health staff diverted from primary work to this response were collected. Productivity losses of quarantined persons were limited to certain age groups and were based on age, sex, and duration of quarantine, so if any of these variables were missing these costs were not included in the analyses. If persons were initially quarantined but subsequently released from quarantine after their immune status was verified, these individuals were not included in the quarantine list and were assumed to have no productivity losses. For productivity losses due to measles illness, time spent at home was based on a survey that took place in the United Kingdom. The time spent away from school or work due to illness might vary by disease severity and public health recommendations (which might differ from country to country) and, thus, results from this survey may not accurately reflect time spent at home in this outbreak. For future research, ideally, surveys would be distributed prospectively at the beginning of the outbreak to all individuals (employees and volunteers) participating in the response to log daily response related time, wages (including benefits and overtime), and material costs. It would also be ideal to survey patients, individuals quarantined, and caregivers to assess lost productivity. Finally, our study was focused on the monetary costs of measles outbreaks and so we did not capture information necessary to estimate health-related utilities or quality-adjusted life-years associated with measles outbreaks.¹⁵ 

Increases in the number of measles cases and outbreaks seen globally translate to increasing costs to society in terms of both disease and economic burden. The potential rippling effects to the local economy when a large number of people are out of work or missing school because of outbreaks can be significant, as experienced during the current coronavirus disease 2019 pandemic.^27–29  In 2019, the United States experienced the greatest number of cases reported since 1992 and since measles was declared eliminated in 2000, resulting in nearly losing elimination status.^30,31  It is likely outbreaks of measles and other vaccine-preventable diseases will continue to occur in the future, particularly in areas with insufficient vaccination coverage. Our estimates of the economic burden a measles outbreak from the societal perspective, in terms of public expenditures to address the measles outbreak, private expenditures incurred as direct medical costs, and productivity losses, indicate that undervaccination can carry a substantial cost for individuals, communities, and public health institutions and underscore the value of vaccination. These estimates can provide valuable inputs for policy makers and public health stakeholders as they consider budget determinations and the substantial value associated with increasing vaccine coverage and outbreak preparedness as well as the protection of society against vaccine-preventable diseases, such as measles, which are readily preventable with high vaccination coverage.

CCPH

Clark County Public Health

CDC

Centers for Disease Control and Prevention

IgM

immunoglobulin M

MV

measles virus

OHA

Oregon Health Authority

PHSKC

Public Health – Seattle & King County

WADOH

Washington State Department of Health