aa‐Prymula 2014.
| Study characteristics | ||
| Methods | RCT ‐ the study was conducted in 111 study centres in Europe: Czech Republic (22), Greece (11), Italy (9), Lithuania (9), Norway (5), Poland (10), Romania (9), Russia (14), Slovakia (17), and Sweden (5). | |
| Participants | N = 5285, healthy children aged 12 to 22 months | |
| Interventions | MMRV group: 2 doses of MMRV (Priorix‐Tetra; GSK, Rixensart, Belgium) N = 2279 MMR+V group: MMR (Priorix, GSK) at dose 1 and monovalent varicella vaccine (Varilrix, GSK) at dose 2, N = 2263 MMR group (control): 2 doses of MMR (Priorix, GSK) N = 743. Doses were administered 42 days apart (Day 0 and Day 42). After completion of this first phase of the clinical trial, MMR+V group participants were offered the second dose of MMR in accordance with the immunisation schedule of their respective country. |
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| Outcomes | The primary efficacy endpoint was occurrence of confirmed varicella (by detection of varicella zoster virus DNA or epidemiological link) from 42 days after the second vaccine dose to the end of the first phase of the trial. Cases were graded for severity. Efficacy analyses were per protocol. | |
| Funding Source | Pharmaceutical industry | |
| Notes | Conclusion: these results support the implementation of 2‐dose varicella vaccination on a short course, to ensure optimum protection from all forms of varicella disease. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Adequate ‐ computer‐generated randomisation list ‐ randomised (3:3:1) ‐ block size 7 |
| Allocation concealment (selection bias) | Low risk | Adequate ‐ centralised randomisation |
| Blinding (performance bias and detection bias) All outcomes | Low risk | Adequate ‐ participants and their parents or guardians, individuals involved in assessment of any outcome, and sponsor staff involved in review or analysis of data were masked to treatment assignment. |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Adequate ‐ < 10% the exclusions are well documented, and seems unlikely that they could have affected the results. |
| Selective reporting (reporting bias) | Low risk | Adequate ‐ all outcomes are reported. |
| Summary Risk of Bias assessment | Low risk | Plausible bias is unlikely to have seriously altered the results. |