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Two studies in monkeys published on Wednesday offer some of the first scientific evidence that surviving COVID-19 may result in immunity from reinfection, a positive sign that vaccines under development may succeed, U.S. researchers said on Wednesday. (Steenhuysen, 5/20)

A prototype vaccine has protected monkeys from the coronavirus, researchers reported on Wednesday, a finding that offers new hope for effective human vaccines. Scientists are already testing coronavirus vaccines in people, but the initial trials are designed to determine safety, not how well a vaccine works. The research published Wednesday offers insight into what a vaccine must do to be effective and how to measure that. “To me, this is convincing that a vaccine is possible,” said Dr. Nelson Michael, the director of the Center for Infectious Diseases Research at Walter Reed Army Institute of Research. (Zimmer, 5/20)

Can people who recover from COVID-19 get it again or do they become immune? That’s been one of the most urgent questions raised by health experts during the coronavirus pandemic, because the answer has sweeping implications. If the antibodies that people produce to fight off the virus do make them immune, they can resume their lives after recovery without fear of reinfection. It also increases the likelihood that scientists can create a vaccine to trigger a similar immune response. (Saltzman, 5/20)

Dan Barouch, director of the center for virology and vaccine research at Beth Israel, and his colleagues were working on a number of candidate DNA coronavirus vaccines in January. Researchers immunized 25 adult rhesus macaques, while 10 others in a control group received “sham versions.”Three weeks vaccination, all 35 animals were exposed to the virus. In follow-up tests, the monkeys that were vaccinated with the coronavirus showed “dramatically lower viral loads” compared with the control group. (Stening, 5/20)