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from Coronavirus herd immunity may be 'unachievable' because antibodies disappear after a few weeks in some people

[www.businessinsider.com]

A major new study in one of Europe's worst affected countries for the coronavirus finds no evidence of widespread immunity to the virus developing.
Just 5% of Spaniards were detected to have antibodies to the virus.
14% of people who previously tested positive for antibodies, tested negative just weeks later.