By CARLA K. JOHNSON, AP Medical Writer COVID-19 has now killed about as many Americans as the 1918-19 Spanish flu pandemic did — approximately 675,000. The U.S. population a century ago was just one-third of what it is today, meaning the flu cut a much bigger, more lethal swath through the country. But the COVID-19 crisis is by any measure a colossal tragedy in its own right, especially given the incredible