I am hoping we do not have to learn about how bad the second wave is before it is too late.

History (Straight from Wikipedia)

Timeline

First wave of early 1918

The pandemic is conventionally marked as having begun on 4 March 1918, with the recording of the case of Albert Gitchell, an army cook at Camp Funston in Kansas, United States, despite there likely having been cases before him.[24] The disease had been observed in Haskell County in January 1918, prompting local doctor Loring Miner to warn the US Public Health Service‘s academic journal.[25] Within days, 522 men at the camp had reported sick.[26] By 11 March 1918, the virus had reached Queens, New York.[citation needed] Failure to take preventive measures in March/April was later criticised.[27]

As the US had entered World War I, the disease quickly spread from Camp Funston, a major training ground for troops of the American Expeditionary Forces, to other US Army camps and Europe, becoming an epidemic in the Midwest, East Coast, and French ports by April 1918, and reaching the Western Front by the middle of the month.[24] It then quickly spread to the rest of France, Great Britain, Italy, and Spain, and in May reached Wrocław and Odessa.[24] After the signing of the Treaty of Brest-Litovsk, Germany started releasing Russian prisoners of war who then brought the disease to their country.[28] It reached North Africa, India, and Japan in May, and soon after had likely gone around the world as there had been recorded cases in Southeast Asia in April.[29] In June an outbreak was reported in China.[30] After reaching Australia in July, the wave started to recede.[29]

The first wave of the flu lasted from the first quarter of 1918 and was relatively mild.[31] Mortality rates were not appreciably above normal;[32] in the United States ~75,000 flu-related deaths were reported in the first six months of 1918, compared to ~63,000 deaths during the same time period in 1915.[33] In Madrid, Spain, fewer than 1,000 people died from influenza between May and June 1918.[34] There were no reported quarantines during the first quarter of 1918. However, the first wave caused a significant disruption in the military operations of World War I, with three-quarters of French troops, half the British forces, and over 900,000 German soldiers sick.[35]

Seattle police wearing masks in December 1918

Deadly second wave of late 1918

The second wave began in the second half of August, probably spreading to Boston and Freetown, Sierra Leone by ships from Brest, where it had likely arrived with American troops or French recruits for naval training.[35] From the Boston Navy Yard and Camp Devens (later renamed Fort Devens), about 30 miles west of Boston, other U.S. military sites were soon afflicted, as were troops being transported to Europe.[36] Helped by troop movements, it spread over the next two months to all of North America, and then to Central and South America, also reaching Brazil and the Caribbean on ships.[37] From Freetown, the pandemic continued to spread through West Africa along the coast, rivers, and the colonial railways, and from railheads to more remote communities, while South Africa received it in September on ships bringing back members of the South African Native Labour Corps returning from France.[37] From there it spread around Southern Africa and beyond the Zambezi, reaching Ethiopia in November.[38] The Philadelphia Liberty Loans Parade, held in Philadelphia, Pennsylvania on 28 September 1918 to promote government bonds for World War I, resulted in 12,000 deaths after a major outbreak of the illness spread among people who had attended the parade.[39]

From Europe, the second wave swept through Russia in a southwest-northeast diagonal front, as well as being brought to Arkhangelsk by the North Russia intervention, and then spread throughout Asia following the Russian Civil War and the Trans-Siberian railway, reaching Iran (where it spread through the holy city of Mashhad), and then later India in September, as well as China and Japan in October.[40] The celebrations of the Armistice of 11 November 1918 also caused outbreaks in Lima and Nairobi, but by December the wave was mostly over.[41]

American Expeditionary Force victims of the Spanish flu at U.S. Army Camp Hospital no. 45 in Aix-les-Bains, France, in 1918

The second wave of the 1918 pandemic was much more deadly than the first. The first wave had resembled typical flu epidemics; those most at risk were the sick and elderly, while younger, healthier people recovered easily. October 1918 was the month with the highest fatality rate of the whole pandemic.[42] In the United States, ~292,000 deaths were reported between September-December 1918, compared to ~26,000 during the same time period in 1915.[33] Copenhagen reported over 60,000 deaths, Holland reported 40,000+ deaths from influenza and acute respiratory disease, Bombay reported ~15,000 deaths in a population of 1.1 million.[43] The 1918 flu pandemic in India was especially deadly, with an estimated 12.5-20 million deaths in the fall months of 1918 alone.[31]

Third wave of 1919

In January 1919, a third wave of the Spanish Flu hit Australia, where it killed 12,000 following the lifting of a maritime quarantine, and then spread quickly through Europe and the United States, where it lingered through the Spring and until June 1919.[12][44][45][41] It primarily affected Spain, Serbia, Mexico and Great Britain, resulting in hundreds of thousands of deaths.[46] It was less severe than the second wave but still much more deadly than the initial first wave. In the United States, isolated outbreaks occurred in some cities including Los Angeles,[47] New York City,[48] Memphis, Nashville, San Francisco and St. Louis.[49] Overall American mortality rates were in the tens of thousands during the first six months of 1919.[50]

Fourth wave of 1920

In spring 1920, a fourth wave occurred in isolated areas including New York City,[48] Switzerland, Scandinavia,[51] and some South American islands.[52] New York City alone reported 6,374 deaths between December 1919 and April 1920, almost twice the number of the first wave in spring 1918.[48] Other U.S. cities including Detroit, Milwaukee, Kansas City, Minneapolis and St. Louis were hit particularly hard, with death rates higher than all of 1918.[53] Peru experienced a late wave in early 1920, and Japan had one from late 1919 to 1920, with the last cases in March.[54] In Europe, five countries (Spain, Denmark, Finland, Germany and Switzerland) recorded a late peak between January-April 1920.[51]