Outbreaks of Gastroenteritis Due to Norovirus in Schools and Summer Camps in Catalonia, 2017–2019

Norovirus is the main cause of viral acute gastroenteritis outbreaks worldwide. The low infectious dose and the lack of long-term immunity in infected persons means that norovirus often causes outbreaks in institutions and closed and semiclosed centers. Norovirus gastroenteritis are usually mild, with no complications, but occasionally can result in hospital admission. Understanding the risk factors involved in a norovirus outbreak can reduce the spread, severity, and duration of the outbreak and, when a vaccine becomes available, this understanding would help us identify the population groups need to get vaccinated. Here, we show the outbreaks due to norovirus in schools and summer camps, the correlation between the delay in reporting and duration of outbreaks and the relationship of the attack rate and the size of the groups.