Evaluation of Risk Factors and Effectiveness of Mass Vaccination Campaign in Response to Serogroup B Meningococcal Disease Outbreak — University of Oregon, 2015

BACKGROUND:  Two vaccines were licensed in October 2014 and January 2015 to prevent invasive serogroup B meningococcal disease (ISBMD), a disease with a 10% fatality rate. During January–May 2015, a total of 7 persons affiliated with the University of Oregon (UO) contracted ISBMD; 1 died. Mass vaccination was recommended to prevent future cases. We evaluated effectiveness of the mass vaccination campaigns.

METHODS:  A case is defined as isolation of serogroup B Neisseria meningitidis since January 2015 from an UO-associated person. We conducted a retrospective cohort study of UO undergraduates to determine groups at highest risk for disease, and surveyed vaccine recipients at the vaccination clinics to measure uptake among populations at risk and evaluate messaging effectiveness.

RESULTS:  UO freshmen were more likely than nonfreshmen (risk ratio [RR]: 8.2; 95% confidence interval [CI]: 1.5–44.7) and sorority and fraternity members more likely than nonmembers (RR: 10.2; CI: 1.9–55.6) to contract ISBMD. To date, 6,362 vaccinees (approximately 90% of clinic attendees) have completed surveys. Although only 29% of registered freshmen and 21% of fraternity and sorority members attended a mass vaccination clinic, they were more likely than nonfreshmen (RR: 2.1; CI: 2.0–2.2) and nonmembers (RR: 1.2; CI: 1.2–1.3) to attend. Respondents reported e-mail as preferred communication method (90%). Concern for contracting ISBMD (65%) and parental request (55%) were most commonly cited motivations for getting vaccinated.

CONCLUSIONS:  As of December 2015, UO continues to experience an ISBMD outbreak. Freshmen and fraternity and sorority members are at higher risk. The vaccination campaign reached populations at risk, but using e-mail and engaging parents might improve uptake among undergraduate populations in ongoing vaccination efforts.