PURPOSE: Influenza virus infection is associated with a high disease burden. COVID-19 caused by SARS-CoV-2 has become a pandemic outbreak since January 2020. Taiwan has effectively contained COVID-19 community transmission. We aimed to validate whether fighting COVID-19 could help to control other respiratory infections in Taiwan. METHOD: We collected week-case data of severe influenza, invasive Streptococcus pneumoniae disease and death toll from pneumonia among 25 calendar weeks of the influenza season for four years (2016-2020), which were reported to Taiwan CDC. Trend and slope differences between years were compared. RESULT: A downturn trend of severe influenza, invasive S. pneumoniae disease and the death toll from pneumonia per week in 2019/2020 season and significant trend difference in comparison to previous seasons were noted, especially after initiation of several disease prevention measures to fight potential COVID-19 outbreak in Taiwan. CONCLUSIONS: Fighting COVID-19 achieved collateral benefits on significant reductions of severe influenza burden, invasive S. pneumoniae disease activity, and the death toll from pneumonia reported to CDC in Taiwan.