Prognosis
Ailments in Covid-19 Trials Raise Questions About Vaccine Method
- Experimental shots from J&J, AstraZeneca based on adenoviruses
- Past experiments with vectors include successes, failures
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Two Covid-19 vaccines stalled by potential side effects have one key feature in common: Both are based on adenoviruses, cold germs that researchers have used in experimental therapies for decades with varying results.
Johnson & Johnson said late Monday it would pause its trial to investigate an illness, which it didn’t specify, in a study participant. Meanwhile, AstraZeneca Plc’s U.S. trial of the vaccine it’s developing with the University of Oxford has been halted by regulators for more than a month after neurological symptoms arose in two volunteers.