How frequent is varicella-associated pneumonia in children?

Varicella is a frequent though mild infection in children, but it can cause important morbidity in adults. The most frequent complication in adults is varicella pneumonia. However, lower airway complications associated to varicella have been scarcely studied in children. We retrospectively reviewed the clinical records of the children hospitalized for varicella-associated pneumonia in the three public hospitals on the Island of Mallorca. We discovered that 17/213 (8%) children hospitalized for varicella were diagnosed of pneumonia. The rate of hospitalization for varicella complication due to pneumonia was 4.3 cases per 10,000 varicella infections. Only one patient was diagnosed of varicella pneumonia, which accounts for 0.3 cases per 10,000 varicella infections. Nine of 17 (53%) cases were classified as bacterial pneumonia. Statistical differences (p < 0.05) in the median time from rash (5.9 vs. 2.4 days) and fever (4.1 vs. 2.2 days) to admission were observed between bacterial and viral pneumonia. However, outcome differences measured by the median length of stay, need for oxygen, and admission to the intensive care unit were not observed. Varicella pneumonia is a very rare complication of varicella in children. Most of the lower airway infections in the course of varicella are associated to other co-infections.