WASHINGTON — A group of former heads of state and Nobel laureates is calling on the United States to immediately commit $5 billion to combat the global coronavirus pandemic, and activists are pressing President Biden to take a more forceful leadership role in the response as he convenes world leaders for a Covid-19 summit on Thursday.

“I want America to recognize that the disease is not over anywhere until it’s over everywhere,” Gordon Brown, a former British prime minister who is leading the push for funding, said in an interview Monday. He added, “We must not sleepwalk into the next variant.”