If you look at the light-grey note at the bottom of the article, you will find this: A version of this article appears in print on September 6, 2014, on page A

If you look at the light-grey note at the bottom of the article, you will find this: A version of this article appears in print on September 6, 2014, on page A10 of the New York edition with the headline: Many in West Africa Are Thought to Be Immune, but Finding Them Will Not Be Easy. So that was the original (printed) title.