| Study characteristics |
| Methods |
Case‐only ecological method study, Italy, to assess the impact of MMRV immunisation programme on varicella‐related hospitalisations |
| Participants |
All hospitalised cases for varicella of all ages |
| Interventions |
MMRV vaccine for children aged 13 to 15 months (first dose) and 5 to 6 years (second dose) or monovalent varicella vaccines for children at 24 months of age. Since July 2008 |
| Outcomes |
From 2004 to 2012, all hospitalised cases for varicella or its complications, as a primary or secondary discharge diagnosis, with the following ICD‐9‐CM codes (2002 and 2007) were examined: 052.0 (post‐varicella encephalitis), 052.1 (varicella (haemorrhagic) pneumonitis), 052.2 (post‐varicella myelitis), 052.7 (varicella with other specified complications), 052.8 (varicella with unspecified complication), and 052.9 (varicella without complication). |
| Funding Source |
Not stated |
| Notes |
Conclusion: the introduction of universal vaccination has already led to a significant decline in hospitalisations due to varicella after just 4 years of implementation. Hospitalisation rates fell noticeably amongst younger individuals involved in the vaccination programme. The decrease in hospitalisation rate in the older age groups suggests a possible indirect protection. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| COEM ‐ case selection |
Low risk |
Adequate ‐ independent validation |
| COEM ‐ exposure |
Unclear risk |
No description |
| COEM ‐ time trend comparison |
Low risk |
Adequate ‐ well‐defined periods |
| COEM ‐ comparability |
Unclear risk |
Stratified by age |
| Summary Risk of Bias assessment |
Unclear risk |
We had concerns regarding at least 1 domain such that some doubt is raised about the results. |
