Panic buying (alternatively hyphenated as panic-buying; also known as panic purchasing) occurs when consumers buy unusually large amounts of a product in anticipation of, or after, a disaster or perceived disaster, or in anticipation of a large price increase, or shortage. Panic buying during various health crises is influenced by "(1) individuals' perception of the threat of a health crisis and scarcity of products; (2) fear of the unknown, which is caused by emotional pressure and uncertainty; (3) coping behaviour, which views panic buying as a venue to relieve anxiety and regain control over the crisis; and (4) social psychological factors, which account for the influence of the social network of an individual". Panic buying is a type of herd behavior. It is of interest in consumer behavior theory, the broad field of economic study dealing with explanations for "collective action such as fads and fashions, stock market movements, runs on nondurable goods, buying sprees, hoarding, and banking panics". Panic buying can lead to genuine shortages regardless of whether the risk of a shortage is real or perceived; the latter scenario is an example of self-fulfilling prophecy. Panic buying occurred before, during, or following: The First (1914-1918) and Second World Wars (1939-1945). The 1918–1919 global influenza pandemic ("Spanish flu") led to the panic buying of quinine and other remedies for influenza and its symptoms from pharmacists and doctors' surgeries. Sales of Vicks VapoRub increased from 2.9 million in a year. In the First Austrian Republic in 1922, hyperinflation and the rapid depreciation of the Austrian krone led to panic buying and food hoarding, which continued until a rescue backed by the League of Nations prevented an economic collapse. Bengal famine of 1943. 1962 Cuban Missile Crisis led to panic buying of canned foods in the United States. The 1973 toilet paper panic in the United States. The 1979 oil crisis led to panic buying of oil, led by Japan.