A day after acknowledging that their COVID-19 vaccine was 90 percent effective when a half-dose was given before a full-dose booster, AstraZeneca Plc and the University of Oxford are facing questions on their trial results.
Earlier on Monday, AstraZeneca and Oxford had claimed that their shot was 70 percent effective on average in a late-stage study. Later, they said that difference in manufacturing processes led to some participants being given a half dose instead of a full one, reports Bloomberg.
Why AstraZeneca-Oxford potential COVID vaccine works better in low dose
Head of the US Operation Warp Speed program has raised an alarm stating that the half-dose was given to some people as a result of an error in the quantity of vaccine put into some vials.
Following this, scientists and investors were rattled on the way vaccine developers have handled the large trial, accusing the firms of sketchy details. AstraZeneca and Oxford, meanwhile, had stated that two full doses showed an efficacy of 62 percent.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
"Any time you have confusion in trials it’s not a good thing because it effectively removes any kind of credibility you had. I think there will be a lot more scrutiny of Astra’s product due to the manufacturing issue," Bloomberg quoted EdenTree Investment Management's fund manager Ketan Patel as saying.
However, the University of Oxford claimed that they discussed with regulators when it was apparent that a lower dose was used. The varsity also stated that an agreement was reached to push ahead with the two regimens.
"The methods for measuring the concentration are now established and we can ensure that all batches of vaccine are now equivalent," Oxford said. Also, AstraZeneca's spokesperson claimed that they are analysing the results to refine the efficacy reading.
With the US drugmakers, Pfizer-BioNTech SE and Moderna claiming about 95 percent effectiveness in preliminary analyses of trials, US Operation Warp Speed program's Dr Moncef Slaoui had said the first Americans to receive a coronavirus vaccine could get it as soon as December 11.
Also, Pfizer had submitted an application to the US Food and Drug Administration for emergency use authorisation last Friday. However, the findings of AstraZeneca's vaccine fired up optimism that an end to the pandemic is in sight.