Varicella-related Primary Health-care Visits, Hospitalizations and Mortality in Norway, 2008-2014.

Abstract

Norway does not currently implement universal varicella vaccination in childhood. We aimed to characterize health care burden of varicella in Norway in the prevaccine era. We linked individual patient data from different national registries to examine varicella vaccinations and varicella-coded primary care consultations, hospitalizations, outpatient hospital visits, deaths and viral infections of central nervous system in the whole population of Norway during 2008-2014. We estimated health care contact rates and described the epidemiology of medically attended varicella infection. Each year approximately 14,600 varicella-related contacts occurred within primary health care and hospital sector in Norway. The annual contact rate was 221 cases per 100,000 population in primary health care and 7.3 cases per 100,000 in hospital care. Both in primary and hospital care, the highest incidences were observed among children 1 year of age: 2,654 and 78.1 cases per 100,000, respectively. The annual varicella mortality was estimated at 0.06 deaths per 100,000 and in-hospital case-fatality rate at 0.3%. Very few (0.2-0.5%) patients were vaccinated against varicella. Among hospitalized varicella patients, 22% had predisposing conditions, 9% had severe-to-very severe comorbidities and 5.5% were immunocompromised. Varicella-related complications were reported in 29.3% of hospitalized patients. Varicella zoster virus was the third most frequent virus found among 16% of patients with confirmed viral infections of central nervous system. Varicella causes a considerable health care burden in Norway, especially among children. To inform the policy decision on the use of varicella vaccination, a health economic assessment of vaccination and mathematical modeling of vaccination impact are needed.