Corona Daily 254: AstraZeneca Vaccine – Trial and Error

On Mon. 9 November, Pfizer released its vaccine news an hour before the opening of the US stock market. Pfizer’s CEO unloaded $5.6 million worth of Pfizer stock at a 52-week high price. Inspired by this, a week later, Moderna announced its 95% effective vaccine on Monday morning. Not surprisingly, AstraZeneca soon followed suit.  On Mon. 23 November, it was the third company to declare the arrival of its vaccine. However, while Moderna’s shares have gone up 22% since its announcement, AstraZeneca fell by 7%. Why did this happen?

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In fact, the AstraZeneca/Oxford vaccine was awaited more than the earlier two. The freezing storage requirement means Pfizer and Moderna are unlikely to be used outside North America and Europe. AstraZeneca, on the other hand, apparently costs less than a cup of coffee. Easy to make, easy to store in a normal refrigerator. India’s Serum Institute has gambled and produced 40 million doses already. Narendra Modi will visit the Indian factory tomorrow. AZ/Oxford vaccine will be the savior of the developing world. UK’s health secretary, Matt Hancock, has already ordered 100 million doses. Boris Johnson said the vaccine has the makings of a wonderful British scientific achievement.

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Pfizer and Moderna had quoted 94-95% effectivity figures. The bar was high. Depending on which newspaper you read, AstraZeneca vaccine was 62%, 70% or 90% effective. Investors rushing to trade didn’t understand what this meant.

The scientific route is to publish the data and results in a reputed medical journal, and get them peer reviewed. This allows the scientists and health authorities to ask relevant questions. All three vaccine companies have opted instead to talk to the Wall Street journalists and offer interim results, before the public or scientists can see the data. In the absence of data, curious people asked: why three figures? And why such a large variation?

Sir Mene Pangalos, the British executive VP at AstraZeneca explained the two versions of the double-dose trial. In one trial, participants received only half a dose the first time, in the other, a full. The second dose was full in both trials. The first trial produced 90% effectivity. The second 62%. The weighted average was 70%.

Rather embarrassingly, the half dose trial produced 90%, and a full dose 62%. Scientists and other people with common sense were puzzled. Then it transpired this half dose trial had happened by accident. It was a manufacturing error made by a contractor. The company explained this as a lucky scientific break.  Who would have guessed half a dose is far more effective than a full dose? (A question that can be set in a SAT test: Effectivity: full dose: 62%, half dose: 90%, no dose:?)

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Meanwhile, Moncef Slaoui, the head of Operation Warp Speed, fortunate to have access to the data, noted that AstraZeneca had limited the half dose trial to those below 55 years of age. This 90% effective vaccine will be first given to doctors and nurses (who may be 55+ as well) and the elderly, but the trial had nobody above 55. With increasingly red faces, the AstraZeneca directors said this was true. All the 2800 participants in the smaller dose regimen were below 55. But there were older people among the 8900 participants who had received two full doses.

The tiny size of the 90% effective trial – 2800 participants – came as another shock. A quick emergency authorization in the USA looked out of question. (It could be the USA vs UK politics as well). Serum institute of India (SII) has produced only the full doses. Hurriedly, SII said it would be ok with the 62% effective vaccine. UK would also be willing to overlook the small matter of half a dose.

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AstraZeneca has now announced it will conduct another global trial with the half dose/full booster regime (90%). At the same time, it will apply for an emergency authorization for the two full doses (62%) regime.

Is it any wonder that the anti-vaxx movement keeps growing?

Ravi