Summary of Winter Outbreaks - 2018/2019 Season

Key Points - Bronchiolitis

• The Hauts-de-France region was the first to enter the epidemic phase this season, with an epidemic trajectory comparable to that of previous seasons.

• Healthcare utilization was similar to that observed in previous seasons, both in emergency departments and at SOS Médecins. Emergency department visits primarily involved children under 6 months of age.

• Nearly one-third of emergency department visits were followed by hospitalization and primarily involved children under 6 months of age.

Key Points - Influenza

• The 2018/2019 flu epidemic was late, short (early January to late February 2019), and particularly severe compared to the two previous seasons. Only type A influenza viruses circulated, with co-circulation of the A(H3N2) and A(H1N1)pdm09 viruses.

• The impact was significant in hospitals, with an increase in emergency room visits compared to previous years, and relatively moderate for SOS Médecins consultations. All age groups were affected, but hospitalizations primarily involved older adults, among whom overall mortality was also the highest.

• The estimate of excess mortality from all causes, extrapolated to the national level during the 9-week epidemic, was +11.8%. The Hauts-de-France region (+14.2%) was among the regions most affected by this excess mortality.

• The surveillance system for severe influenza cases hospitalized in intensive care shifted this season from a comprehensive system to a sentinel mode. Fifteen adult and pediatric intensive care units are participating in Hauts-de-France, spread across 6 healthcare facilities. With a total of 98, the number of severe cases reported this season was lower than in the 2017/18 season (185) but higher than in the 2016/17 season (64 cases). All cases were infected with a type A virus.

Key Points - Gastroenteritis

• As in previous years, two waves occurred in succession due to the circulation of different viruses. The first wave, likely caused by norovirus, led to an increase in healthcare utilization across all age groups, both at SOS Médecins and in emergency departments. The second wave, caused by rotavirus, led to an increase in emergency department visits only among children under 5 years of age.

• The impact of gastroenteritis on emergency department visits and subsequent hospitalizations is all the more significant the younger the patients are. This age-related difference is less pronounced at SOS Médecins.