Preliminary analysis from the pharmaceutical company AstraZeneca and partner University of Oxford shows its COVID-19 vaccine candidate is highly effective at preventing disease. Pitt continues to recruit participants as one of the trial sites.
In its Nov. 23 announcement, AstraZeneca said one dosing regimen showed vaccine efficacy of 90% when the vaccine AZD1222 was given as a half dose, followed by a full dose at least one month later. Another dosing regimen showed 62% efficacy when given as two full doses at least one month apart.
“It’s exciting to see these results because all the vaccines we’re testing here in Pittsburgh are using the spike protein. It’s just how you get that spike into human cells without it getting destroyed that’s different,” said Sharon Riddler, associate professor of medicine at Pitt, who is leading the Pittsburgh site of the Phase 3 trial for this vaccine.
Pittsburgh is one of more than 100 trial sites for the vaccine being developed by AstraZeneca and Oxford. The Pittsburgh site is still enrolling participants, and people can sign up to volunteer at www.pvtu.org. Pitt is also a local site for Moderna’s Phase 3 clinical trial, as well as Johnson & Johnson’s, which are both being led by Judy Martin, who directs the Pittsburgh Vaccine Trials Unit at UPMC Children’s Hospital of Pittsburgh and serves as a professor of pediatrics.
The AstraZeneca vaccine is what’s known as a “viral vector.” A mild virus (an adenovirus, like those that cause the common cold) is engineered to carry the coronavirus’ spike protein, which prompts an immune response inside the body. The adenovirus is also altered so it doesn’t spread throughout the body.
The Moderna and Pfizer vaccines, meanwhile, use mRNA that codes for spike proteins found in COVID-19. Cells in the body use those mRNA instructions to make a spike protein, which generates an immune response.
Also, unlike the Moderna and Pfizer vaccines, which need to be stored at freezing or extremely cold temperatures, the AstraZeneca vaccine can be stored at temperatures comparable to a household refrigerator.
Despite the seemingly comparable vaccine efficacy rates for AstraZeneca, Pfizer and Moderna, Riddler cautions against comparing the effectiveness of these vaccine candidates.
“We don’t have the data. I feel really excited and good about it, but I think we need to see the data, and it takes some time for it to come together,” she said. “We need more time. We need more info. But it’s all exciting.”
While it remains to be seen which vaccines will be made available first, Graham Snyder, associate professor in Pitt’s School of Medicine Division of Infectious Diseases, said once detailed data on safety and efficacy has been published, UPMC will evaluate the data and make available any vaccine deemed safe and effective.
“That data might influence which specific populations we'd recommend for each vaccine, but our communities can rest assured that we've got robust plans in place to handle, store and distribute all of the vaccines,” Snyder said.