| Study characteristics |
| Methods |
Retrospective cohort ‐ Singapore |
| Participants |
Children attending childcare centres and primary schools in 1999. Childcare centres (N = 2533) and primary schools (N = 2539) |
| Interventions |
MMR vaccination status of each child (MMR or nothing) was obtained from health booklet (updated in Singapore when a child receives vaccination in accordance with the immunisation schedule). The specific strain type (Rubini, Jeryl Lynn, Urabe, or unknown mumps strain) was identified by matching the batch number of vaccine in health booklet with the record of the vaccine in polyclinic or family doctor's clinic. Even if the number of administered doses was not indicated, it can be supposed that only older children could have received a second MMR dose, as it was routinely introduced in January 1998. |
| Outcomes |
Mumps: clinically defined as fever associated with unilateral or bilateral swelling and tenderness of 1 or more salivary glands, usually the parotid gland. Diagnosed by physician. Serological confirmation was not carried out. |
| Funding Source |
Government |
| Notes |
Authors' conclusions: "Our study confirms the low protection conferred by the Rubini vaccine strain" |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| PCS/RCS ‐ exposed cohort selection |
Unclear risk |
Probably representative of the exposed, but number of administered doses was not indicated |
| PCS/RCS ‐ non‐exposed cohort selection |
Low risk |
Adequate ‐ drawn from the same community |
| PCS/RCS ‐ comparability |
Unclear risk |
Probable residual confounding ‐ the cohort was limited to affected classes |
| PCS/RCS ‐ assessment of outcome |
Unclear risk |
Only clinical definition |
| Summary Risk of Bias assessment |
Unclear risk |
We had concerns regarding at least 1 domain such that some doubt is raised about the results. |
