The COVID-19 vaccine produced by Oxford University and AstraZeneca is nearing approval in the United States after an independent study showed there is no link between the treatment and blood clotting, and a Phase III trial posted strong efficacy and safety results.
The so-called Oxford vaccine showed 79 percent efficacy at stopping symptomatic COVID-19 infection and 100 percent efficacy at preventing severe disease and hospitalization, according to a late-stage trial of more than 32,000 participants in the U.S., Chile and Peru.
Anglo-Swedish pharmaceutical company AstraZeneca also said on Monday that an independent data safety monitoring board had found no link between the vaccine and an increased risk of blood clotting.
The latter analysis comes after numerous European countries temporarily paused distribution of the jab following a small number of cases of blood disorders among vaccinated individuals. Health bodies including the World Health Organization and European Union and United Kingdom drug regulators have since run investigations which found no connection between the treatment and raised rates of blood clotting.
The Phase III results will also help allay concerns over issues in previous late-stage trials. In one study conducted last year, a laboratory error led to a large number of participants receiving an incorrect dosage, meanwhile data from two trials was pooled, rather than presented separately, which some experts said was a methodological error.
Vaccine efficacy was consistent across ethnicity and age, the trial found, including in participants aged 65 years and older, for which efficacy was 80 percent. Efficacy is particularly important in older age groups, where severe illness is more common.
"This analysis validates the AstraZeneca COVID-19 vaccine as a much-needed additional vaccination option, offering confidence that adults of all ages can benefit from protection against the virus," said Ann Falsey, who is a professor of medicine at the University of Rochester in the U.S., and co-lead principal investigator for the trial.
AstraZeneca is now preparing the data from the trial which it will submit to the U.S. Food and Drug Administration, which is responsible for authorizing treatments. The Oxford vaccine would be the fourth jab to gain approval in the U.S., in addition to shots from Moderna, Johnson& Johnson, and Pfizer and BioNTech.
The Oxford and Johnson &Johnson jabs have a logistical advantage in that they can be stored at normal refrigeration temperatures for several months, whereas the Pfizer and BioNTech treatments require ultra-cold storage.
"We are confident this vaccine can play an important role in protecting millions of people worldwide against this lethal virus," said Mene Pangalos, who is executive vice president for biopharmaceuticals research and development at AstraZeneca. "These results add to the growing body of evidence that shows this vaccine is well tolerated and highly effective against all severities of COVID-19, and across all age groups."
