evidence: Misinformation about mask use has circulated since the beginning of the COVID-19 pandemic. Claims that wearing face masks increase the risk of infection are not new and were previously found to be inaccurate, as reported in Health Feedback reviews here and here. In October 2020, numerous social media posts on Facebook and Twitter claimed that the majority of "Spanish flu" deaths were due to bacterial pneumonia caused by wearing masks. The claim is based on a 2008 study published in the Journal of Infectious Diseases and co-authored by Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases[1]. [...] Multiple experts debunked the claim that masks cause bacterial pneumonia. Davidson Hamer, a professor of global health and medicine at Boston University stated, "There’s no evidence of masks leading to fungal or bacterial infections of the upper airway or the lower airway as in pneumonia." [...] In summary, the claim that the 2008 study by Fauci and co-authors observed a causal link between deaths from the Spanish flu due to bacterial pneumonia and the use of face masks is inaccurate. The study makes no mention of masks, and no scientific study to date establishes a causal association between mask use and increased risk of bacterial pneumonia in the general population.