The White House said the president had received an IV infusion of a cocktail of antibodies manufactured by Regeneron Pharmaceuticals, of Tarrytown, New York. That treatment is essentially a way to mimic a powerful immune response in order to ward off a serious case of covid-19.
https://www.technologyreview.com/2020/10/02/1009278/what-drug-treatments-will-president-trump-get/