As immunocompromised people across the country work to get Evusheld, a potentially lifesaving covid therapy, several hundred providers of the injections were removed from a federal dataset on Wednesday night, making the therapy even harder to locate. White House officials had announced March 15 that a planned purchase of more doses would have to be scaled back without new federal funding. And federal and state health departments aren’t making it easy to find, leaving patients whose hospitals say they don’t have enough of the drug to write desperate tweets and Facebook posts seeking the shots w…