| Study characteristics |
| Methods |
Retrospective cohort ‐ vaccine effectiveness in primary cases and in households |
| Participants |
Children attending primary schools and their household contacts. Schools were eligible when they had at least 1 laboratory‐confirmed mumps case or more than 1 clinical mumps case. |
| Interventions |
MMR vaccine. Parents of schoolchildren were asked to fill out a questionnaire asking for information on the child's vaccination status (since 2007). To define the vaccination status, the study authors used individual information registered in the national Dutch vaccination register (‘Praeventis’). Information on vaccination status for 69 pupils (6%) could not be obtained from this register (66 no informed consent, 3 unknown vaccination status in register). For these children, authors used the self‐reported vaccination status (vaccinated/not vaccinated), assuming for vaccinated children that 1 dose was received when the child was aged < 8.75 years, and 2 doses when the child was aged ≥ 8.75 years. |
| Outcomes |
Mumps cases were defined by affirmative answer (by parental report) to the question "has your child had mumps after September 2007?". |
| Funding Source |
Government |
| Notes |
The vaccine effectiveness was based on the clinical disease of mumps only. VE is provided adjusted for possible confounders. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| PCS/RCS ‐ exposed cohort selection |
Unclear risk |
National register or self‐reported |
| PCS/RCS ‐ non‐exposed cohort selection |
Unclear risk |
National register or self‐reported |
| PCS/RCS ‐ comparability |
Unclear risk |
There was insufficient information. |
| PCS/RCS ‐ assessment of outcome |
Unclear risk |
By questionnaire |
| Summary Risk of Bias assessment |
Unclear risk |
We had concerns regarding at least 1 domain such that some doubt is raised about the results. |
