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LESS than a year after a new kind of coronavirus started spreading around the globe, we have several vaccines that seem to be very effective at producing strong enough immune responses to protect people from developing covid-19.

Despite this great news, however, critical questions remain about how our immune system responds to the virus. Speaking at an , Devi Sridhar at the University of Edinburgh, UK, listed some of the gaping holes in our knowledge. “How long does immunity last? Can you …