A coronavirus drug derived from immune cells of Covid survivors gives better protection than vaccines after six months and could last for a year, trial results suggest.

AstraZeneca today announced that its antibody injection AZD7442 reduces the risk of symptomatic Covid by 83 per cent six months after a single dose.

In contrast, vaccines can wane substantially in the months following an injection, even after two doses, with the AstraZeneca vaccine falling to around 40 per cent effectiveness, and Pfizer about 60 per cent.

The company said the artificial antibodies appeared to last longer than the vaccine and a single injection could offer protection for a year, although have not yet been trialled in large populations.

The vaccines also initially showed higher protective effect in trials than real-world settings, although were hampered by the emergence of the Delta variant. In contrast, AZD7442 was trialled at a time when Delta was rampant.

Hugh Montgomery, professor of intensive care medicine at University College London, AZD7442 principal investigator, said: “These compelling results give me confidence that this long-acting antibody combination can provide my vulnerable patients with the long-lasting protection they urgently need to finally return to their everyday lives. 

“Importantly, six months of protection was maintained despite the surge of the Delta variant among these high-risk participants who may not respond adequately to vaccination.”

A separate trial shows the drug also reduces the risk of severe Covid and death by 88 per cent when given within three days of symptom onset.

Potential breakthrough in treatment for elderly and vulnerable

The injection could be a breakthrough in treatment for elderly and immunocompromised people who cannot mount an adequate immune response against the virus, even after vaccination. 

The research of both trials has been submitted for peer review, and is expected to be published in the coming weeks. 

About one in 50 people does not make an adequate response to the vaccine, and the treatment could also be useful to helping protect at-risk groups, such as elderly people living in care homes. 

Groups who could benefit include people with cancer who are being treated with chemotherapy, patients on dialysis, or those taking medication to suppress their immune systems following, such as people undergoing organ transplants, those with arthritis or people with multiple sclerosis. 

The drug, which only needs to be administered in a single dose, is a combination of two antibodies which are derived from immune B-cells donated by convalescent patients who had recovered from the virus.

The antibodies bind to sites on the spike protein which the virus uses to enter cells. 

AstraZenca said it had been designed to last for three times as long as conventional antibodies and a single dose could give protection for up to 12 months.

The drug is also currently in trials as a potential treatment for hospitalised Covid patients. 

Mene Pangalos, executive vice president, BioPharmaceuticals R&D, AstraZeneca, said: “AZD7442 is the only long-acting antibody with Phase III data to demonstrate benefit in both pre-exposure prophylaxis and treatment of Covid-19 with one dose. 

“These new data add to the growing body of evidence supporting AZD7442’s potential to make a significant difference in the prevention and treatment of Covid-19.”

The company has now submitted the findings to regulators who are deciding whether to grant approval to the new treatment.  

AstraZeneca has already agreed to supply the US Government with 700,000 doses of AZD7442 if granted an emergency use authorization by the FDA, and has agreements to supply to other countries.