Key Points

The 2017–2018 winter season was marked by an early and prolonged influenza epidemic (from week 49 of 2017 to week 12 of 2018) that had a significant impact on hospitals. The epidemic was dominated by the A(H1N1)pdm09 virus during the early phase, then by the Yamagata lineage B virus starting in week 7 of 2018. The epidemic resulted in excess mortality from all causes of approximately 17,900 deaths (1,770 in the region). The region was one of the least affected in terms of excess mortality. However, the case fatality rate for severe influenza cases was higher than the national average (24% versus 18%). During this epidemic period, 341 influenza cases were hospitalized in the region’s intensive care units, which is four times more than in the two previous years (n=85).The severity of the 2017–2018 winter epidemic is also evident in the high number of reports of clusters of acute respiratory infections (ARI) in long-term care facilities (LTCFs), though fewer than in the previous winter (159 vs. 215 the previous season). Vaccination coverage among individuals targeted for influenza vaccination remains low, with approximately 51% of people aged 65 and older vaccinated during the 2017–2018 season in Nouvelle-Aquitaine.

The 2017-2018 winter season was also marked by a moderate-scale bronchiolitis epidemic that began early and was relatively short-lived compared to the previous two seasons, with the epidemic starting in week 47 of 2017 and lasting 7 weeks (through week 1 of 2018). However, a resurgence of bronchiolitis cases in late January led to a prolonged post-epidemic period lasting until mid-February.

The acute gastroenteritis epidemic during the winter of 2017–2018 was prolonged. Activity remained sustained from early November through late March, with a peak in early January in outpatient care and emergency departments. Overall, the acute gastroenteritis (AGE) epidemic during the 2017-2018 winter began earlier and was less severe than the previous winter, except among children under 5 years of age.

Surveillance of winter illnesses for the 2018–2019 season will differ from previous seasons, with sentinel surveillance of intensive care admissions, the discontinuation of surveillance for acute gastroenteritis (AGE) cases in long-term care facilities, and a change in AGE surveillance in the general population.