AstraZeneca COVID-19 vaccine can be 90% effective, results show

They showed that the vaccine had an efficacy of 62 percent among the people given two full doses a month apart. The combined analysis from both dosing regimens showed an average efficacy of 70%, according to press releases from AstraZeneca and Oxford.

AstraZeneca's proposed vaccine produced less effective results when compared with others produced by rivals BioNTech/Pfizer and Moderna, which were shown to be over 90% effective. That's a relatively unproven technology when it comes to human therapeutics, which involves using messenger RNA to provide blueprints to a person's body to build proteins effective at blocking a virus, without any virus present.

Pollard said that although this was not routine practice in vaccines and added a layer of complexity to its manufacturing, it makes more sense in terms of optimising resource use to guarantee a higher level of protection.

The Phase 3 trial for the Oxford vaccine included 24,000 participants, and it's expected to grow to 60,000 by the end of the year.

Trials of the AstraZeneca Oxford vaccine were carried out around the world, including in the United Kingdom, the US, Japan, Russia, South Africa, Kenya and several Latin American countries.

This is great news for potential vaccination programs, since it introduces variety of supply chain into an apparently effective vaccine treatment for COVID-19.

Peter Openshaw, professor of experimental medicine at Imperial College London, said the finding that a smaller initial dose is more effective than a larger one is good news because it may reduce costs and mean more people can be vaccinated.

The AstraZeneca trial looked at two different dosing regimens.

No serious safety events related to the vaccine occurred in the studies, AstraZeneca said. "But the immune system does not work like that".

"The report that an initial half-dose is better than a full dose seems counterintuitive for those of us thinking of vaccines as normal drugs: With drugs, we expect that higher doses have bigger effects, and more side-effects", he said.

The British drugmaker's preliminary trial results mark a fresh breakthrough in the fight against a pandemic that has killed almost 1.4 million people and roiled the global economy.

"Clinical trials are also being conducted in the US, Japan, Russia, South Africa, Kenya and Latin America with planned trials in other European and Asian countries", it added. AstraZeneca has pledged to "ensure broad and equitable access to the vaccine at no profit for the duration of the pandemic".

"So I just wanted to thank people from all of us for this enormous thing that they have done to help us and everybody get out of the Covid hole".

"By using only half the normal dose, the 40 million projected doses before the end of the year could then become 80 million", Cheng pointed out.

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