| Study characteristics |
| Methods |
Retrospective cohort study in Spain assessing the effectiveness of MMR vaccination against clinical mumps on preschool and schoolchildren during an outbreak (March to November 1997) |
| Participants |
Male children aged between 3 and 15 years attending 1 scholastic institute in the district of Cartuja y Almanjàyar (N = 775), which had the highest mumps attack rate in the district |
| Interventions |
MMR immunisation (school, vaccination or register by the local health centre) Composition and strains not reported. |
| Outcomes |
Parotitis. Clinical defined by surveillance (case definition: unilateral or bilateral swelling of parotids or salivary glands, sensible to tasting, lasting more than 2 days, that appears without apparent cause or without contact with affected children) |
| Funding Source |
Government |
| Notes |
It was not possible to assess mumps strain types administered to study population. In Spain, Urabe (AM9 strain) was used until 1993, after which it was replaced by Jeryl Lynn and Rubini. Even if cases are those identified by surveillance, there is no description in the report of how it has been performed (e.g. active or passive surveillance?). In any case, in the paragraph on case definition, the authors declare that included cases are only those identified by surveillance and that real cases are unknown (underestimated). |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| PCS/RCS ‐ exposed cohort selection |
Low risk |
Adequate ‐ register by the local health centre |
| PCS/RCS ‐ non‐exposed cohort selection |
Low risk |
Adequate ‐ register by the local health centre |
| PCS/RCS ‐ comparability |
High risk |
No information reported. |
| PCS/RCS ‐ assessment of outcome |
High risk |
Very unclear reporting |
| Summary Risk of Bias assessment |
High risk |
We had concerns regarding multiple domains such that our confidence in the result is substantially lowered. |
