The above plot shows worldwide overall total influenza counts per year, using WHO flunet data (2024 data are only available through April). Percent positivity indicates the number of positive influenza tests as a percent of the total number of specimens received for influenza testing and is represented by the red line. Percent positivity was very high in 1996 (63%) but then dropped, likely due to a change in testing practices. This is especially apparent in years after 2020, represented by the dashed vertical line. For example, total influenza cases in 2022 increased to 983,357 but percent positivity for influneza was only 8%. This suggest that many specimens were collected for testing, but were influenza negative. This is likely due to combined testing for several respitory viruses, including COVID 19 and RSV.
Data source:
Flunet. https://www.who.int/tools/flunet.