Severe chickenpox disease and seroprevalence in Sweden - implications for general vaccination
K Widgren1, L Persson Berg2, A Mörner3
1Department of Medicine, Huddinge, Karolinska Institute, Stockholm, Sweden; Department of Public Health Analysis and Data Management, the Public Health Agency of Sweden, Solna, Sweden.
Insights
Severe chickenpox complications occurred in healthy children, supporting universal vaccination. Adult migrants were a hospitalization risk group, with seroprevalence similar to neighboring countries.
Area of Science:
- Infectious Diseases
- Immunology
- Public Health
Background:
- Chickenpox (varicella) remains a concern, particularly severe cases requiring hospitalization.
- Understanding current disease burden and population immunity is crucial for vaccination policy decisions.
Purpose of the Study:
- To assess the current landscape of severe chickenpox and seroprevalence in Sweden.
- To provide data supporting the evaluation of universal childhood vaccination strategies.
Main Methods:
- Retrospective review of hospitalized chickenpox patients (ICD-10 B01-B01.9) in Stockholm and Gothenburg (2012-2014).
- Analysis of serum samples from 11 Swedish laboratories for varicella-zoster virus IgG antibodies to determine age-specific seroprevalence.
Main Results:
- Hospitalized cases included 218 children and 46 adults; 87.2% of children and 63.0% of adults experienced complications.
- Common complications in children were dehydration, bacterial skin infections, and neurological issues. Adult cases frequently involved individuals born abroad.
- Seroprevalence reached 66.7% by age 5 and 91.5% by age 12. Infants and adolescents/adults were disproportionately represented in hospital admissions compared to seroprevalence data.
Conclusions:
- The high rate of complications in previously healthy children underscores the benefit of universal childhood vaccination.
- Adult migrants represent a vulnerable group for severe chickenpox requiring hospitalization.
- Sweden's age-specific varicella seroprevalence aligns with that of neighboring countries.
Objectives:
To describe the current panorama of severe chickenpox disease and seroprevalence in Sweden, as a basis for the approaching decision on universal vaccination.
Methods:
Patients discharged with an International Classification of Diseases 10th revision-code for chickenpox (B01-B01.9) in eight pediatric and infectious diseases departments in Stockholm and Gothenburg in 2012-2014 were included in the study and their medical charts were reviewed. Further, residual serum samples collected from 11 laboratories across Sweden were analyzed for varicella zoster IgG-antibodies to investigate age-specific seroprevalence.
Results:
A total of 218 children and 46 adults were included in this hospital-based study; 87.2% of children and 63.0% of adults had complications. An underlying condition was not associated with an increased risk of complication. Dehydration (31.7%), bacterial skin infections (29.8%) and neurological involvement (20.6%) were the most frequent complications in children. Among adult cases, 63% were born abroad. The seroepidemiological analysis included 957 patient samples. Seroprevalence was 66.7% at 5 years and 91.5% at 12 years. Infants and adolescents/adults were overrepresented among admitted patients compared to seroprevalence data.
Conclusions:
Half of all complications in hospitalized chickenpox cases were seen in previously healthy children, which supports universal childhood vaccination. Adult migrants was a risk group for chickenpox hospitalization. Age-specific seroprevalence was similar to neighboring countries.
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