Effectiveness of previous mumps vaccination during a summer camp outbreak.
OBJECTIVE
Mumps is a vaccine-preventable disease that may cause outbreaks. In July 2005, an outbreak of mumps occurred during a children's summer camp in upstate New York. An investigation was initiated to describe the cases and evaluate vaccine effectiveness.


METHODS
A retrospective cohort study was conducted among 541 children from the United States and abroad who attended a 1- or 2-month overnight summer camp. Patients with mumps were interviewed; serologic analysis was conducted for 6 case patients. Vaccine effectiveness was calculated by retrospective review of immunization records for 507 attendees who were eligible for vaccination and had verified immunization history.


RESULTS
Thirty-one camp attendees were identified as having mumps (attack rate: 5.7%); 5 (83%) of 6 patients tested had positivity for mumps immunoglobulin M. Of the 507 participants (including 29 patients) with available immunization history, 440 (including 16 [87%] patients) were 2-dose recipients of mumps vaccine (attack rate: 3.6%); 46 participants (including 4 [9%] patients) were 1-dose recipients (attack rate: 8.7%); and 21 (including 9 [4%] patients) were unvaccinated (attack rate: 42.9%). Vaccine effectiveness was 92% for 2 doses and 80% for 1 dose.


CONCLUSIONS
Outbreaks of mumps in settings such as summer camps can occur despite high vaccination rates. Vaccine effectiveness for 2 mumps vaccinations was greater than vaccine effectiveness for 1 mumps vaccination. Therefore, recommendation of 2 mumps vaccinations for summer camp participants continues to be appropriate. Control of mumps disease relies on broad vaccination coupled with correct clinical diagnosis and strict control measures.
Schaffzin
Joshua K
JK
Epidemic Intelligence Service, Office of Career Workforce and Development, Centers for Disease Control and Prevention, Atlanta, Georgia, USA. jks05@health.state.ny.us
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D000293:Adolescent; D000328:Adult; D000368:Aged; D000914:Antibodies, Viral / Q000032:analysis; D002165:Camping; D002648:Child; D015331:Cohort Studies; D004196:Disease Outbreaks; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D008875:Middle Aged; D009107:Mumps / Q000453:epidemiology* / Q000517:prevention & control*; D009108:Mumps Vaccine / Q000008:administration & dosage*; D009109:Mumps virus / Q000276:immunology; D009518:New York / Q000453:epidemiology; D012189:Retrospective Studies; D016896:Treatment Outcome; D014611:Vaccination / Q000706:statistics & numerical data
D000914:Antibodies, Viral; D007075:Immunoglobulin M; D009108:Mumps Vaccine