AstraZeneca's eagerly awaited COVID-19 vaccine passes large test, but confirmation needed

AstraZeneca R&D, Boston, USA
(AstraZeneca)

As Moderna, Pfizer and BioNTech have this month been busy releasing early data out of their COVID-19 vaccine programs, AstraZeneca is now joining the July data drop.

And it’s broadly good news: The trial of the vaccine, known as AZD1222 and being developed by AstraZeneca and scientists at the University of Oxford, was generally safe (fevers and headaches hit the majority but could be controlled), and it saw both antibody and T-cell immune responses.

Whether this is enough to create a strong and lasting immunity against SARS-CoV-02, the virus causing COVID-19, remains the bigger question, and longer-term follow-up trials will be needed to confirm this (and are ongoing).

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But patience is not a key word in this pandemic, and the U.K. has already ordered 100 million doses of the vaccine, despite it not being approved, although Oxford has previously said the vaccine could be approved in some form as early as September.

So, the early peek at the data looks like this: The phase 1/2 trial saw around 500 patients given the AZ/Oxford vaccine, also known as ChAdOx1 nCoV-19, and compared the results to those from around the same number getting a meningococcal vaccine.

For the AZ vaccine, antibodies against the SARS-CoV-2 spike protein peaked by day 28 and remained elevated to day 56, indicating an immune response against the virus. Much has recently also been made of so-called T cells, a type of white blood cell: Here, the vaccine levels of T cells peaked 14 days after vaccination and were still present two months later.

The median age was 35, much younger than the group which will need it most, i.e., those over 70, and the majority of those getting the AZ vaccine had aches, headaches, fever and fatigue, though there doesn’t appear to be anything more serious. These were generally controlled with paracetamol.

Professor Andrew Pollard, Ph.D., chief investigator of the Oxford Vaccine Trial and co-author of the study, said: “The interim phase 1/2 data for our coronavirus vaccine shows that the vaccine did not lead to any unexpected reactions and had a similar safety profile to previous vaccines of this type.

“The immune responses observed following vaccination are in line with what we expect will be associated with protection against the SARS-CoV-2 virus, although we must continue with our rigorous clinical trial programme to confirm this. We saw the strongest immune response in participants who received two doses of the vaccine, indicating that this might be a good strategy for vaccination.”

Mene Pangalos, AZ's executive vice president for biopharmaceuticals R&D, added: “We are encouraged by the phase 1/2 interim data showing AZD1222 was capable of generating a rapid antibody and T-cell response against SARS-CoV-2. While there is more work to be done, today’s data increases our confidence that the vaccine will work and allows us to continue our plans to manufacture the vaccine at scale for broad and equitable access around the world.”

Later-stage trials are now underway in the U.K., Brazil and South Africa and are due to start in the U.S. These trials “will determine how well the vaccine will protect from the COVID-19 disease and measure safety and immune responses in different age ranges and at various doses,” according to AstraZeneca. These studies will be the real litmus test.

The vaccine works by being molded from a genetically engineered virus that causes the common cold in chimpanzees and is designed to make it look enough like the virus to fool the immune system into learning how to attack it should the real SARS-CoV-02 infect a patient, but not enough to actually cause that patient to come down with the disease.

This is a different approach than that coming from Pfizer and partner BioNTech, CureVac and Moderna, three other major COVID-19 vaccine players using mRNA, which could prove more speedy but has never seen a drug or inoculation approved using this MOA before.

Shares in AstraZeneca have been climbing over the past week on the highly anticipated data but fell a few percentage points when the The Lancet’s publication came out midafternoon U.K. time. The company has said it will not be seeking a profit from the vaccine during the pandemic.

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