Reconciling estimates of the global influenza burden

Influenza remains an important cause of morbidity and mortality, even in high-income countries. Yet quantification of its burden is contentious. Although influenza virus infections are commonly associated with respiratory symptoms, some infections can cause more severe disease, resulting in hospitalisation or death. Influenza can also trigger other health outcomes—eg, acute myocardial infarction1 which probably arises because infection stimulates inflammation, atherosclerosis, and coronary lesions.