The TLDR: AstraZeneca disclosed the data from its late stage trials of the Oxford vaccine. It is on average 70% effective—but a modified version offers 90% protection. The performance may not seem as dazzling as that of Pfizer and Moderna—which showed 95% efficacy—but this vaccine may yet prove to be the most effective in protecting the world’s population. Also: This is brilliant news for Indians!

The basic deets

Here’s how this vaccine works. 

• Scientists took a weakened version of the common cold virus from chimpanzees. They modified the virus so it can’t grow in humans. 
• Then they added the genes of the spike protein from the coronavirus. 
• When injected, our cells start to produce only the spike protein (not the virus itself). 
• Our body detects its presence and produces antibodies and killer T-cells that attack the infection. 
• These remain in our body protecting us when we encounter an infected person.

What’s different: The use of modified cold viruses is a fairly established medical technology—already used in vaccines for TB, malaria and Ebola. In comparison, Pfizer and Moderna are mRNA vaccines which have never been developed before (explained here).

Ok, now tell me about its trial data

The results are based on human trials held in the UK and Brazil—and involved more than 20,000 participants. Of these, 30 people who received two doses of the injection developed Covid. There were 101 infections among those who received the placebo. Most importantly, no one who received the vaccine developed severe symptoms, or had to be hospitalized.

But here’s the weird bit: When volunteers were given two "high" doses, percentage protected was only 62%. But the number rose to 90% when people were given a "low" dose followed by a high one. The researchers don’t know exactly why, but their best guess: “We think that by giving a smaller first dose, that we're priming the immune system differently. We're setting it up better to respond.”

Also, this half-dose outcome was a stroke of luck. Doctors in the UK administered less than the required amount to some participants by sheer accident. The lead researcher doesn’t know why this is so but thinks it’s good news: “It means we will have a lot more doses to distribute if that way of vaccinating was approved.” 

Point to note: Other experts warn that the 90% efficacy of the half-dose regimen may prove to be a statistical anomaly as further trials are held—since it is only based on 2,741 participants. Also this: AstraZeneca-Oxford also released fewer details than Pfizer and Moderna. Variations in their methodology and reporting also makes direct comparisons very difficult. For example:

“In the AstraZeneca trial in Britain, researchers counted infections by swabbing participants weekly. That detection method was likely to have turned up more infections than the trials run by Moderna and Pfizer, which tested people who developed symptoms and may have failed to find any asymptomatic cases.”

Is it good enough?

Before Pfizer and Moderna revealed their superlative results, anything above 50% would have been considered a triumph just a month ago. Also: 70% is way more effective than the seasonal flu jab. 

In fact, this is far better news for the rest of the world—including India.

Why is it better news than Pfizer?

One: Pfizer and Moderna are kinda like the ‘rich man’s’ Covid vaccine. They are way pricier than Oxford—which is selling the vaccine at cost ($4-5) in order to keep it affordable. It is being manufactured by the Pune-based Serum Institute of India—which has agreed to sell it to the government for Rs 220 per dose. Individuals sourcing it privately will pay Rs 600. In comparison, Moderna plans to charge $32-37 per dose, while Pfizer’s two-jab regimen will cost $39. As a Human Rights Watch researcher noted, “Those prices really risk putting vaccines out of reach for a lot of the world.”

PS: A Mumbai travel company is already hawking a Rs 1.75 lakh trip to the US for super-rich clients who want to get a Pfizer jab.

Two: All of the initial supply of the Pfizer and Moderna vaccines have been pre-booked by wealthy countries—including the UK, US, EU and Japan. In contrast, AstraZeneca has made deals to supply 3.2 billion doses to more than 50 lower- and middle-income countries across the world—including Latin America, Africa, the Middle East, Asia and Eastern Europe. It is also a member of the global Covax alliance to ensure equitable distribution of the vaccine—unlike Moderna or Pfizer. 

Three: Most importantly, it is the easiest to transport to remote corners of the world and India. The reason: It can be stored in a normal refrigerator at 2°C to 8°C. Moderna (minus 20°C) requires a freezer, while Pfizer—which needs to be kept at minus 70°C—has to be stored in a special case. That’s a near-impossible task in warmer and/or poorer nations—including India (as we explained here).

Four: We live in a highly interconnected world. A vaccine that works for some nations and not others will not end the pandemic. As one British expert points out: “It’s not just a problem for people over there, far away from us. This is a problem for most people in the world.”

When will we get this vaccine?

Availability: Serum Institute plans to apply for emergency use authorisation based on the trial data—but officials say analysis can take anywhere from days to weeks. But Serum has already manufactured 40 million doses, and will have another 60 million in 45-60 days. Of these, 90% will be sold to the Indian government.

First in line: The government is readying plans to vaccinate one crore healthcare workers—who will get whichever vaccine is available early next year. The health ministry earlier announced its aim to vaccinate 250 million people with 500 million doses of the vaccine by July 2021. But these will again target the most vulnerable groups: frontline workers, the elderly and people with underlying conditions. 

The rest of us: Now, 10% of those 100 million Serum doses are reserved for private consumers. But an unnamed source told The Telegraph “that there was still uncertainty over when Serum could make the vaccine available for the country’s private market. ‘This will depend on what quantity the government orders.’” 

The bottomline: Immunology expert Danny Altmann best sums up where we are: “For the bigger picture, my suspicion is that by the time we are a year down the line, we’ll be using all three vaccines with about 90 per cent protection—and we’ll be a lot happier.” And hurrah for that!

Reading list

Vox has the most detailed overview of the Oxford vaccine—both pluses and minuses. The Telegraph and Indian Express have the most reporting on implications for India. Bloomberg News explains why this vaccine is far more critical to vaccinating the world. Now that we may be rolling out a vaccine soon, it may be good to revisit our explainer on delivery challenges in India. Reuters profiles Serum Institute of India—which is the largest vaccine manufacturer in the world.