Highly anticipated trial results for a coronavirus vaccine candidate AstraZeneca (AZN 0.41%) 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.
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.