The Phase 3 clinical study showed that the drug – a combination of two long-acting antibodies – was able to reduce the risk of developing symptoms of COVID-19 by 77% compared to administration to patients who had not yet been exposed to the coronavirus. No patient who received the drug, called AZD7442, developed the severe form of the disease. Meanwhile, in the placebo arm, three patients developed severe COVID-19, and two of them died.
The company said it would submit the results to a peer-reviewed review and use them to support a regulatory case for the drug.
AstraZeneca officials said the drug could be used especially as a preventative treatment in patients for whom vaccines might not be very effective. Some patients with weakened immune systems, for example because they have received an organ transplant, have been shown not to respond as effectively to COVID-19 vaccines.
Mene Pangalos, executive vice president of AstraZeneca, praised the results and said more tools were needed to help people at high risk “not sufficiently protected by COVID-19 vaccines”.
The study result was based on the 25 cases of symptomatic COVID-19 that developed, out of a total of 5,172 participants who were not positive for the coronavirus at the start of the trial. AstraZeneca said more than 75% of trial participants had comorbidities that made them more susceptible to the virus
AZD7442 uses monoclonal antibodies, which mimic the body’s natural defenses to target the virus. AstraZeneca said the antibodies had been modified to make them more durable and could potentially “offer up to 12 months of protection against COVID-19 after a single administration.”
An earlier study of the drug, which viewed it as a treatment for COVID-19 in patients who had previously been exposed to the virus, returned negative results in June.