N680 Module 3 assignment: discussion post on an outbreak investigation, a full sample

Module 3 Discussion: Initial Post

Two Doses Were Not Enough: What the Arkansas Mumps Outbreak Asked of Public Health Nurses

For this discussion I chose the mumps outbreak that began in northwest Arkansas in August 2016, because it shows how an outbreak investigation depends on nurses as much as on laboratories. Before 2016, the state health department investigated between one and six mumps cases a year. Over the next twelve months it received reports of more than 4,000 suspected cases and identified 2,954 outbreak cases, 57% of them in children aged 5 to 17 and 57% among Marshallese residents, a Pacific Islander community of recent migrants (Fields et al., 2019). The most striking finding was that 92% of the school-aged patients had already received two doses of mumps-containing vaccine.

The investigation followed the usual steps: confirming the diagnosis, establishing a case definition, finding cases, describing them by person, place and time, and implementing control measures. Cases were confirmed by laboratory testing or classified as probable if they had symptoms and either a positive blood test or a link to a confirmed case. Two features made this outbreak unusual. The virus spread readily among vaccinated people, and it spread fastest in households with many members living closely together, where exposure was intense and prolonged. The authors described the outbreak as primarily affecting a marginalized community with intense household crowding and called for coordinated, interdisciplinary and nontraditional responses (Fields et al., 2019).

That call is where public health nurses come in. Counting cases required finding them, and finding them required trust. Nurses worked with Marshallese community leaders, churches and interpreters to explain isolation, which for a school-aged child meant five days at home, and why it mattered even for a child who had been vaccinated. Nurses ran school-located and community vaccine clinics, followed up contacts by phone and in homes, and answered the question families most often asked: if my child had two shots, why did they get sick? Answering honestly meant explaining that two doses reduce the risk substantially but do not eliminate it, and that protection appears to decline in the years after the second dose.

The outbreak also became part of the evidence for a new policy. A study of an outbreak at a university in Iowa found that students who received a third dose had a 78.1% lower risk of mumps 28 days after vaccination than those with two doses, and that students whose second dose was 13 or more years earlier had a much higher risk (Cardemil et al., 2017). In January 2018, the national immunization committee recommended a third dose for people identified by public health authorities as being at increased risk during an outbreak (Marin et al., 2018). Arkansas had already offered third doses in affected schools and communities before that national recommendation, and much of that vaccination work fell to public health nurses.

Two lessons stand out for my own practice. First, vaccination status alone does not tell us who is protected; household crowding, time since vaccination and access to care shaped this outbreak more than any single factor. When I read a case table now, I ask what the living conditions of the people in it are. Second, many Marshallese families lost Medicaid eligibility under a 1996 federal law and did not regain it until 2020, which means that during the outbreak many families had no regular source of care. A public health nurse who knew that would plan clinics in churches and schools rather than expect families to come to a clinic.

I would like to hear from classmates who have worked in outbreaks: how did you explain vaccine failure to families without undermining their trust in vaccination itself?

References

Cardemil, C. V., Dahl, R. M., James, L., Wannemuehler, K., Gary, H. E., Shah, M., Marin, M., Riley, J., Feikin, D. R., Patel, M., & Quinlisk, P. (2017). Effectiveness of a third dose of MMR vaccine for mumps outbreak control. New England Journal of Medicine, 377(10), 947-956. https://doi.org/10.1056/NEJMoa1703309

Fields, V. S., Safi, H., Waters, C., Dillaha, J., Capelle, L., Riklon, S., Wheeler, J. G., & Haselow, D. T. (2019). Mumps in a highly vaccinated Marshallese community in Arkansas, USA: An outbreak report. The Lancet Infectious Diseases, 19(2), 185-192. https://doi.org/10.1016/S1473-3099(18)30607-8

Marin, M., Marlow, M., Moore, K. L., & Patel, M. (2018). Recommendation of the Advisory Committee on Immunization Practices for use of a third dose of mumps virus-containing vaccine in persons at increased risk for mumps during an outbreak. MMWR Morbidity and Mortality Weekly Report, 67(1), 33-38. https://doi.org/10.15585/mmwr.mm6701a7