AstraZeneca, Oxford Fortifying COVID-19 Vaccine Against Viral Variants

AstraZeneca and the University of Oxford said they are working “as rapidly as possible” to tailor their COVID-19 vaccine for significant new coronavirus mutations and believe the revamped vaccine will be ready in the fall — and that their existing vaccine has been shown to reduce transmission of disease.

The “next generation” vaccine is being specifically designed to be more effective against new COVID-19 variants that could hamper efficacy, including the worrisome UK and South African strains that have put vaccine-makers on the defensive. While currently authorized COVID-19 vaccines still appear to protect against the variants, the South African strain in particular has shown that it’s able to at least reduce effectiveness, and both strains appear highly contagious.

Andrew Pollard, director of the Oxford Vaccine Group and chief investigator of Oxford’s vaccine trial, said that the modified vaccine will not require anywhere near the enormous efforts seen for the vaccine’s late-stage trials, which have enrolled tens of thousands of participants. By comparison, trials for the updated shot will probably be miniscule.

“The process for starting with an edited version, a slight change to the vaccine, is a really short process in comparison to the huge efforts last year to run very large-scale trials. These are really likely to be very small trials that can be run quickly,” Pollard said during a press briefing.

“I think it’s important to recognize that the virus is going to continue to mutate in response to the immunity that is developing in populations around the world,” he noted.

The efforts to update the AZ/Oxford vaccine come along with marvelous news that the vaccine has been shown to reduce transmission of disease by up to 67 percent, according to a primary analysis of data from their UK, Brazil and South Africa trials. The data, which came from both phase 3 and phase 1/2 trials, suggest that the vaccine could not only save lives and prevent illness but also help to cut the spread of the virus, which could prove invaluable for getting the pandemic under control.

While the researchers did not conduct actual transmission studies, they took weekly swabs from UK trial participants regardless of symptoms and found that a single vaccine shot reduced positive results in polymerase chain reaction (PCR) tests by 67 percent. Following the second dose, positive test results were cut by nearly half (49.5 percent).

“These data indicate that [the AZ vaccine], used in the authorized schedules, may have a substantial impact on transmission by reducing the number of infected individuals in the population,” the researchers said.

The analysis, which appeared as a preprint in The Lancet, also showed that the vaccine fully protected against severe disease, hospitalization and death more than 22 days after the first dose and showed 76 percent efficacy three weeks after the first dose. That efficacy bumped up to 82 percent after the second dose was given three months later. The vaccine’s second-dose efficacy after 12 weeks could help mitigate the burdens of any supply constraints countries may encounter, the researchers said.

“Vaccination programs aimed at vaccinating a large proportion of the population with a single dose [of the AZ vaccine], with a second dose given after a three-month period, is an effective strategy for reducing disease and may be the optimal for rollout of a pandemic vaccine when supplies are limited in the short term,” they said.

Pollard said that there are more data to come, especially on the vaccine’s effectiveness in older adults, and he expects AZ’s phase 3 U.S. trial to report data soon, though he did not give a specific timeline. — James Miessler