Measles and mumps are highly infectious viral diseases which can lead to serious complications such as meningitis and encephalitis. Though these 2 diseases are vaccine preventable diseases, re-emergence and recurrent outbreaks are reported worldwide. Vaccine reluctance and/or non-compliance to recommended vaccination schedules are the primary reasons for these resurgences. However, it cannot be excluded that the genetic diversity of circulating measles and mumps strains may affect the effectiveness of the available measles, mumps and rubella (MMR) vaccines.
In 1988, routine immunisation against measles and mumps was introduced in the UK as part of a combined MMR vaccine. Both MMR-II (MSD) and Priorix (GSK) vaccines are available in the UK market with MMR-II vaccine being the most in use. The UK recommended MMR vaccination following a schedule with a first dose between 12 and 15 months of age and a second dose at 30 months of age.
Limited data on the effectiveness of Priorix has been reported to date. Therefore, this study will aim to assess the effectiveness of Priorix against the 2 highly contagious diseases, measles and mumps, in children born after 2004 in the UK.
The aim of this study is to assess the effectiveness of Priorix vaccine against measles and mumps diseases in children born after 2004. The vaccine effectiveness (VE) will be evaluated for at least 1 dose (primary objective) and for 1 dose and 2 doses (secondary objectives) of Priorix. VE against measles and mumps diseases will be assessed separately on 2 distinct study populations.
The study will be an observational, retrospective, matched case-control study with a targeted case-control ratio of 1:4. All children born after 2004 and with first diagnosis of measles or mumps disease between January 2006 and December 2018 will be included in the study as cases. Cases will be identified from the Clinical Practice Research Datalink (CPRD) and Hospital Episode Statistics (HES) databases by using disease specific medical codes (CPRD medical codes and International classification of diseases [ICD]-10 codes according to the source data). The index date will be the date of the diagnosis of the first reported event. Control subjects will be matched by month and year of birth and practice region. Exposure to Priorix will be identified by using the batch number variable available in the CPRD database.
A conditional logistic regression will be applied to compute odds ratio. The model will be adjusted for index for multiple deprivation (IMD) and number of consultations during the year prior to index date as covariates. VE will be calculated using the following formula:
VE=1- (odds of exposure in case group/odds of exposure in control group).
Health Outcomes to be Measured:
Measles disease and mumps disease reported in primary care and in hospital setting.
HES Admitted;Patient IMD;Practice IMD (Standard)