Drugmaker AstraZeneca announced on November 23 that its experimental Coronavirus vaccine has shown an average efficacy of 70 percent in its large scale trials -- the latest of several vaccine trials worldwide to post their results this month. The vaccine, developed with the University of Oxford, showed 90 percent efficacy in half a dose of the vaccine followed by a full dose at least one mont apart, and 62 percent efficacy in a second regimen using two full doses on month apart.

The vaccine was developed by the British-Swedish pharmaceutical company AstraZeneca in collaboration with the University of Oxford and is also known as AZD1222.

In September, AstraZeneca has paused all clinical trials of the Covid-19 vaccine it is developing with Oxford university after a participant in the UK section of the study suffered a suspected serious adverse reaction. The UK-based drugmaker voluntarily put the trial on hold after the discovery of the sick participant, who fell ill with a rare inflammatory condition called transverse myelitis, according to two people familiar with the trial. Trial restarted on November 12.

More than 23,000 adults are currently being assessed in the trials, with the number expected to rise to up to 60,000, the statement said. Early results suggested there were 131 cases of Covid-19 among the participants but none was serious.

How do AstraZeneca, Moderna, and Pfizer jabs compare?

Moderna’s vaccine has to be stored at minus 20 Celsius, up to a month. Pfizer’s should be kept at minus 70 degrees Celsius. However, the Oxford jab is far cheaper and is easier to store and get to every corner of the world than the other two.

“Today marks an important milestone in our fight against the pandemic,” AstraZeneca’s chief executive, Pascal Soriot, said.

“This vaccine’s efficacy and safety confirm that it will be highly effective against Covid-19 and will have an immediate impact on this public health emergency.”

Professor Andrew Pollard, the chief investigator of the Oxford Vaccine Trial, said that “these findings show that we have an effective vaccine that will save many lives.”

Stock market reaction

Stocks are off to a good start on Wall Street on November 23 after AstraZeneca said that late-stage trials showed that its coronavirus vaccine was up to 90 percent effective.

The S&P 500 rose 0.9 percent in the early going Monday (Nov. 23) following a loss last week. Companies that would benefit the most from a reopening of the economy were among the early winners, including energy producers.

Though there have been positive developments about vaccines, it will be many months before large swathes of the population receive them. In the meantime, virus cases are still rising rapidly and the economic impact is being felt. The US hopes to get 300 million doses by January from its investment program to fast-track a successful vaccine, says the BBC.

But not all countries are in a position to do likewise. Although the pharmaceutical companies will be making the vaccine, they won't be the ones who decide who gets vaccinated first.

AstraZeneca, which has promised not to profit from the vaccine "for the duration of the pandemic," said it will now immediately prepare to submit the data to regulators around the world -- including in the United Kingdom, Europe, and Brazil -- that have a framework in place for conditional or early approval. The company will also seek an emergency use listing from the World Health Organization for an accelerated pathway to vaccine availability in low-income nations.

The partners said Monday that there were no confirmed serious safety events related to the vaccine and that it was well tolerated across different dosing regimens.