Abstract: A method of treating COVID-19 in a patient. The patient may be in moderate to advanced stages of COVID-19 infection. The method includes administering to the patient a therapeutically effective amount of at least one antagonist or inhibitor of chemokine receptor CXCR4. The at least one antagonist or inhibitor of chemokine receptor CXCR4 is distinct from hydroxychloroquine.

Abstract: Severe influenza is associated with defects in pulmonary innate immunity, a phenomenon leading to secondary bacterial infections. The gut microbiota can control immune/inflammatory responses locally and at distant sites. The inventors hypothesized that perturbation of the gut microbiota during severe influenza might participate in bacterial superinfection post-influenza. Their data demonstrated that influenza infection profoundly altered the functionality of the gut microbiota as assessed by the altered production of short chain fatty acids (SCFAs). Remarkably, treatment of colonized (IAV microbiota) mice or IAV-infected mice with acetate, the main SCFA found systematically, reinforced host defenses against S. pneumoniae. The present invention thus relates to the use of short-chain fatty acids for the treatment of bacterial superinfections post-influenza.