As waves of new coronavirus variants circulate the globe, one thing has become clear: human immunity against the virus fades over time.
Mandatory Credit:	THOMAS KIENZLE/AFP via Getty Images

As waves of new coronavirus variants circulate the globe, one thing has become clear: human immunity against the virus fades over time.
Mandatory Credit: THOMAS KIENZLE/AFP via Getty Images

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The quest for longer-lasting Covid-19 vaccines

As waves of new coronavirus variants circulate the globe, one thing has become clear: human immunity against the virus fades over time.