Highly anticipated trial results for a coronavirus vaccine candidate AstraZeneca (NYSE:AZN) licensed from Oxford University reached The Lancet, a major medical journal, on Monday. And they put the adenovirus-based candidate, called AZD1222, firmly in the lead in the race to develop vaccines that can end the COVID-19 pandemic.  

This was a big early-stage trial with 1,077 healthy patients randomized to receive a single injection of AZD1222 or a meningitis vaccine as a control. The investigators also gave 10 patients in the AZD1222 group a booster shot after 28 days. 

A blood vial with a

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In terms of safety, the results fell somewhere between pretty good and wonderful. There weren't any serious adverse events related to AZD1222, but some patients did report injection-site pain and symptoms that could be mistaken for an actual COVID-19 infection. More than 20% of patients who were given AZD1222 reported moderate fever and fatigue.

It's too early to measure the number of COVID-19 infections in each group to gauge AZD1222's efficacy, but signs of an immune response that might stop SARS-CoV-2, the virus that causes COVID-19, were encouraging. Antibodies that glom onto the spike protein that SARS-CoV-2 uses to enter host cells reached peak production 28 days after injection and remained at high levels during a 56-day evaluation.

Oxford and AstraZeneca have already begun larger phase 3 clinical trials in Brazil, the U.K., and South Africa. A similar U.S. study to measure how many people injected with AZD1222 get COVID-19 compared with those given a placebo should begin shortly.