The first of many COVID-19 vaccine doses are making their way to distribution sites across the U.S., as the nation’s pandemic deaths approach the bleak and horrifying milestone of 300,000. The rollout of the Pfizer vaccine, the first to be approved by the Food and Drug Administration, ushers in the biggest vaccination effort in U.S. history — one that health officials hope the American public will embrace, even as some have voiced initial skepticism or worry, Martha Irvine and Morry Gash report. The first of two shots is expected to be given in the coming week to health care workers and nursing home residents. Nursing Home Worry: After 110,000 deaths ravaged America’s nursing homes and pushed them to the front of the vaccine line, they now face a vexing problem: skeptical residents and workers balking at getting the shots. Being first has come with fears that the places hit hardest could be put at risk again by vaccines sped into development in mere months, that their effects have not been fully studied, and that the frail and those who care for them will essentially be test subjects. Federal health officials say testing has uncovered no serious side effects and they are launching a $250 million ad campaign to sway those with doubts to get the vaccines, Bernard Condon and Matt Sedensky report. Trump Vaccine: He says he’s reversing an administration directive to vaccinate top government officials while public distribution of the shot is limited to front-line health workers and people in nursing homes and long-term care facilities. Trump made the announcement in a tweet , hours after his administration confirmed that senior U.S. officials, including some White House aides who work in close proximity to Trump and Vice President Mike Pence, would be offered coronavirus vaccines as soon as this week under federal continuity of government plans, Zeke Miller reports. Racing for a Remedy: Teams of researchers around the globe are now studying the places and species from which the next pandemic may emerge. Even as the world struggles with COVID-19 devastation, scientists say this pandemic likely won’t be the last. Many scientists are focusing attention on the world’s only flying mammals — bats. Viruses that emerge from bats are more lethal in humans than those from other species. Christina Larson, Aniruddha Ghosal and Marcelo Silva de Sousa report.