Determinants of varicella breakthrough: results of a 2012 case control study
Silvio Tafuri1, Rocco Guerra1, Maria Giovanna Cappelli1
1Department of Biomedical Science and Human Oncology; Aldo Moro University of Bari; Bari, Italy.
Insights
The time between varicella vaccination and virus exposure was longer in children who experienced breakthrough infections. This duration is a key factor in determining vaccine effectiveness after one dose.
Area of Science:
- Immunology
- Vaccinology
- Pediatrics
Background:
- Breakthrough varicella infections can occur despite vaccination.
- Understanding determinants of vaccine failure is crucial for public health strategies.
Purpose of the Study:
- To identify risk factors for breakthrough varicella infections after one dose of the varicella vaccine.
- To evaluate the association between time from vaccination and breakthrough disease.
Main Methods:
- Retrospective case-control study design.
- Inclusion of 45 breakthrough varicella cases and 135 controls (children aged 1-15).
- Data collection on vaccination status, time from vaccination, and presence of risk factors.
Main Results:
- No significant difference in the proportion of cases and controls with at least one risk factor (40% vs. 39.2%).
- A longer time interval between varicella vaccination and viral exposure was observed in breakthrough cases.
- Logistic regression identified the duration of time from vaccination as significantly associated with breakthrough disease.
Conclusions:
- The time elapsed since varicella vaccination is a significant determinant of breakthrough infection.
- While general risk factors were similar, the timing of vaccination relative to exposure plays a critical role in vaccine effectiveness.
Abstract:
This study aims to evaluate the determinants of breakthrough infection after one dose of varicella vaccine. We designed a retrospective case-control study. Breakthrough cases were children, aged 1-15, who presented varicella symptoms ≥ 42 days after the first dose of varicella vaccine (breakthrough). Controls were children, aged 1-15 years, who attended the same class (in a school or in a kindergarten) than the cases in the year of the breakthrough onset; they received a dose of varicella vaccine ≥ 42 days before the case rash onset and they did not develop varicella symptoms. We enrolled 45 cases and 135 controls. 40% of cases (n = 18; 95% CI = 25.4-54.6) presented at least one risk factor; this proportion was 39.2% (95% CI = 30.9-47.6) among the controls (chi-square = 0.0078; P = 0.93). Time between vaccination and virus exposure was longer among cases. Logistic regression showed that breakthrough disease was associated with duration of time from vaccination.
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