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New research on how some people had a level of Covid immunity before the pandemic started. Blood samples showed hospital staff being monitored in the first wave already had protective \\u2018killer\\u2019 T-cells probably from exposure to other viruses related to the one that has swept the globe. The difference between antibodies to an infection and antibodies caused by a vaccine. And the extraordinary story of a woman who rid her body of HIV.
Presenter: Claudia Hammond\\nProducer: Erika Wright
(Picture: Microbiologist studying coronavirus. Photo credit: Janiecbros/Getty Images)
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