【英文】世卫组织报告：世卫组织新冠病毒溯源联合研究报告（120页）

The weekly percentage of ILI cases in both children and adults in the sentinel surveillance in Wuhan in  2019 laboratory-confirmed to be due to influenza virus infection was compared with the weekly  percentages in the previous three years (Annex E1). There was considerable week-to-week variation in  the proportion reported positive for influenza virus in both children and adults, with the percentage  generally being lower between week 15 and week 40 and higher between week 40 and week 15 of the  next year (consistent with the usual seasonal influenza activity). The rise in influenza virus infections,  as a proportion of ILI, is apparent in both children and adults at the end of 2019: in children this rise is  comparable to rises seen in earlier years; in adults the steep rise in ILI due to influenza virus infection  at the end of 2019 is apparent but the percentage positive is little different to that seen at the end of  2016. Only about 20 samples per week were tested.

In 2019, most ILI cases in Hubei Province as in Wuhan city were reported in children (Fig. 4). As in  Wuhan (Fig. 1), the weekly number of ILI cases in Hubei Province (and the percentage of all  consultations categorized as ILI) rose steeply from week 49 in 2019.  The weekly percentage of ILI cases in Hubei Province in 2019 laboratory-confirmed to be due to  influenza virus infection showed less week-to-week variation than the percentage observed for Wuhan  alone (likely owing to the larger denominator of ILI cases across the whole province) but exhibited the  same general trend of higher rates before and after the end of the year and lower rates in the middle of  the year (Annex E1).