TABLE 2

Mumps ARs Among Sixth- to 12th-Grade Students During Selected 3-Week Periods Before and After a School-Based Third-Dose MMR Vaccine Intervention During an Outbreak of Mumps, Orange County, New York, 2009–2010

Prevaccination (21 d)Postvaccination Phase 1a (21 d)Postvaccination Phase 2b (21 d)Comparison of ARs in Postvaccination Phase 2 and Postvaccination Phase 1
No. of Mumps CasesPopulation at RiskAR (%)No. of Mumps CasesPopulation at RiskAR (%)No. of Mumps CasesPopulation at RiskAR (%)RR (95% CI)P
All studentsc
 All students11322914.933522581.55322230.130.06 (0.02–0.19)<.001
 Females4112613.251512561.19312410.240.21 (0.06–0.73).006
 Males7210306.992010022.0009820.00NCd<.001
Students with a validated history of 2 previous MMR vaccine doses
 Students who did not receive a third dose of MMR vaccine74201.6724130.480.3 (0.06–1.40).18e
  Females22340.8522320.861.0 (0.14–7.10)1.0e
  Males51862.6901810.00NCd.06e
 Students who received a third dose of MMR vaccine2817511.60117230.060.04 (0.005–0.27)<.001
  Females139841.3219710.100.08 (0.01–0.59)<.001
  Males157671.9607520.00NCd<.001
  • a Day 1 to day 21 after the vaccination date.

  • b Day 22 to day 42 after the vaccination date.

  • c Refers to students in the eligible 3 schools who did not have a history of mumps and who had not received a third dose of MMR vaccine before the vaccination date.

  • d NC: Could not be calculated because of empty cells.

  • e P value calculated by using the Fisher exact test.