Estimates of vaccine effectiveness against measles and mumps: 14 years follow-up of a large cohort in Wales, UK
Source: PubMed Central Open Access, NCBI / U.S. National Library of Medicine
Abstract Background Uptake of the measles–mumps–rubella vaccine in Wales is high. However, sporadic measles cases still occur and there are large mumps outbreaks every few years. In this study, the long-term vaccine effectiveness (VE) of vaccines containing measles and mumps is assessed. s1 Methods A retrospective cohort of 822 116 individuals aged 1–30 years were followed up between 1 January 2007 and 31 December 2020. Welsh Demographic Service data were linked to vaccination status from the national vaccination register and primary care records. Outcomes were identified by linking to laboratory confirmations (measles and mumps) and notifications (mumps) data. Complications were sourced from hospital admissions and primary care data. Extended Cox regression was used to calculate hazard ratios. s2 Results The adjusted VE (aVE) against confirmed measles after two doses remained high after 15 years 99.7% [95% confidence interval (CI) 99.2–99.9]. The aVE for confirmed mumps was lower, with decline over time: 93.6% (95% CI 90.2–95.8) in the first 5 years after vaccination with dose two and 49.9% (95% CI 34.4–61.8) after ≥15 years. A third dose of mumps vaccine temporarily increases protection (87.6%, 95% CI 71.7–94.6). The aVE estimates for mumps were lower when based on clinical suspicion. The VE was high against complications for both infections. s3 Conclusion The high, sustained VE for measles strengthens evidence that elimination remains possible and the high VE against mumps
Abstract
Abstract Background Uptake of the measles–mumps–rubella vaccine in Wales is high. However, sporadic measles cases still occur and there are large mumps outbreaks every few years. In this study, the long-term vaccine effectiveness (VE) of vaccines containing measles and mumps is assessed. s1 Methods A retrospective cohort of 822 116 individuals aged 1–30 years were followed up between 1 January 2007 and 31 December 2020. Welsh Demographic Service data were linked to vaccination status from the national vaccination register and primary care records. Outcomes were identified by linking to laboratory confirmations (measles and mumps) and notifications (mumps) data. Complications were sourced from hospital admissions and primary care data. Extended Cox regression was used to calculate hazard ratios. s2 Results The adjusted VE (aVE) against confirmed measles after two doses remained high after 15 years 99.7% [95% confidence interval (CI) 99.2–99.9]. The aVE for confirmed mumps was lower, with decline over time: 93.6% (95% CI 90.2–95.8) in the first 5 years after vaccination with dose two and 49.9% (95% CI 34.4–61.8) after ≥15 years. A third dose of mumps vaccine temporarily increases protection (87.6%, 95% CI 71.7–94.6). The aVE estimates for mumps were lower when based on clinical suspicion. The VE was high against complications for both infections. s3 Conclusion The high, sustained VE for measles strengthens evidence that elimination remains possible and the high VE against mumps complications is encouraging. Evidence for the waning of mumps immunity may be important when deciding to implement a third dose in outbreak settings. With the increased use of data linkage, studies should be conducted to corroborate these findings. s4