According to Alfred W. Crosby,
America's Forgotten Pandemic: The Influenza of 1918, about 4500 American troops arrived in Archangel on the White Sea on Sept. 4, 1918, to assist the anti-Bolshevik forces. By the time they were pulled out in June 1919, they had suffered 192 deaths, including 112 killed or mortally wounded in action and 72 killed by disease--mostly by the Spanish flu. The Americans brought the flu virus to that isolated corner of Russia and an unknown number of Russians died from it--undoubtedly many thousands.
Crosby calls the counterrevolutionary regime based in Archangel "feckless."