The Spanish Flu (COVID) hit all the fighting powers during WWI.

The least available data for Western researchers afterwards was Russia and the Ottoman Empire, who suffered COVID losses.

Strangely enough, of the Allied powers, the British suffered much less COVID deaths than the French, US, Italians.

One theory is that many of the British imperial soldiers from all over the world already had been exposed to COVID and therefore developed immunities.

When they got sick, they didn't die like the Allied soldiers.

During the Spanish-American War (1898), less than 400 Soldiers were killed by the Spaniards during that four month conflict, but approximately 15,000 US soldiers died from disease.