Outbreak of Hepatitis A in a Nursery School

In a background of very low incidence of hepatitis A HA in the last decade (annual average of 1.8 cases per 100,000 inhabitants) we describe an outbreak of HA which evolved in Mallorca between May and August 2010, whose main focus was a nursery school where more cases were parents and other young relatives of the children of the institution. Thirty-four cases were defined as outbreak cases. Ten were children of the nursery or their siblings and 22 adults (3 staff members of the nursery and 19 relatives; median age 33 years). The first detected cases were children of the same class. There were 2 adults with haematological complications, though not severe. All children, nursery staff members, parents, and siblings of the cases of the first affected class were immediately offered HA vaccination, but only 43.3% eligible individuals accepted it. None of the cases had been vaccinated. The outbreak spread mostly from asymptomatic children to young adults, showing the changes in HA pattern. That is of great concern as the risk of severe illness rises with age. This incident shows the need to implement new HA vaccination policies in outbreak control. This was later carried out.