The TLDR: Pfizer—in partnership with German company BioNTech—announced that their vaccine candidate is “90% effective.” The stock markets went nuts, and the medical community welcomed the news. But is this really a big deal? Yes, maybe—and for India especially, it is a bit of a mixed bag. We explain.

First, the vaccine explained

Traditional vaccines inject live or dead bits of the virus into a human body—which then triggers the production of protective antibodies. This is how we become ‘immune’ when we get a jab. But Pfizer is developing a unique messenger RNA (or mRNA) vaccine, which works like this:

• We are instead injected with genetic material taken from the virus.
• This teaches our cells to produce the spike protein of the coronavirus—which is harmless in itself. In Bill Gates' words, “you essentially turn your body into its own manufacturing unit.”
• When our body detects these proteins, it launches the required immune response.
• mRNA vaccines are faster and cheaper to produce because we don’t need large samples of the virus itself. 
• And the hope is that they will trigger not just antibodies, but also T-cells which kill the virus at the cellular level.
• Point to note: This vaccine requires two shots, administered three weeks apart.
• If Pfizer’s candidate is approved, it will be the first mRNA vaccine ever.

Next, the results

Pfizer released the interim results of its late stage trials, and declared that it was 90% effective. The top US Covid expert Anthony Fauci called the results “just extraordinary,” and the WHO said the vaccine could “fundamentally change the direction of this crisis.” Most experts had warned that early vaccines may only be 60-70% effective.

Defining 90%: Pfizer has 43,538 people enrolled in its late stage trials around the world. Of these, 38,955 have received two injections of the candidate or a placebo. Of these, 94 developed Covid-19. But of these 94, fewer than nine actually received both shots of the vaccine. Hence, it is 90% effective—or rather has 90% efficacy!

Effectiveness vs efficacy: As Quartz points out, there’s a big difference between those two words in the world of medicine:

“‘Efficacy’ is what is demonstrated, to varying degrees, by a vaccine in a randomized trial like Pfizer’s. The same vaccine’s ‘effectiveness’ is based on observational studies, once the shot is deployed in the real world. A vaccine’s effectiveness may not be the same as its efficacy.”

Translation: What works in the carefully controlled conditions of a trial may not work as “effectively” when there are millions of people with vastly varying health and living conditions.

Also this: There’s lots of information we don’t have as yet:

“There is no information yet on whether the vaccine prevents severe cases, the type that can cause hospitalization and death. Nor is there any information yet on whether it prevents people from carrying the virus that causes Covid-19, SARS-CoV-2, without symptoms… Because the vaccine has been studied for only a matter of months, it is impossible to say how long it will protect against infection with the virus.”

Unique challenges of a unique drug

Even if the Pfizer vaccine is the first to be approved, it isn’t exactly a miracle drug that will save the world. There are three key challenges.

One: It won’t be easy to ramp up production of this vaccine. Pfizer says it will only have enough to vaccinate about 20 million people by the end of 2020. And there will be 1.3 billion doses by the end of 2021—which can vaccinate about 650 million people. Point to note: each person needs two doses.

Two: This vaccine needs to be stored in sub-zero conditions—minus 80°C to be precise from the moment they are bottled to the time they are ready to be injected into the patients’ arms. As the New York Times notes:

“Pfizer has designed a special box to transport its hoped-for vaccine. The boxes, roughly the size of a large cooler, will hold a couple of hundred glass vials, each containing 10 to 20 doses of vaccine. The boxes are equipped with GPS-enabled thermal sensors, allowing Pfizer to know where the boxes are and how cold they are. (If they get too warm, workers can add dry ice.)”

And that’s a huge challenge for warm countries like India with limited cold storage facilities. As Mint notes:

“India has 80,000 cold storage units that are used for vaccination supplies today. To vaccinate 250 million people, the country would need 10 times more this number, an executive from an Indian vaccine manufacturer who did not want to be identified, estimated. Depending on the technology platform, storing a covid vaccine may require temperatures ranging from an extreme of -70 degrees centigrade to eight degrees centigrade. Today, India has no capability of storing at -70°C, the executive said.”

Three: Unlike other countries, Pfizer isn’t funded by any government and is not part of the WHO vaccine consortium. As its CEO made clear: “I wanted to liberate our scientists from any bureaucracy. When you get money from someone...that always comes with strings.” But that also means, it isn’t clear who will get Pfizer’s vaccine if it is the first to be approved. The company has struck a deal to supply the US with 100 million doses—and double that with the EU. Other agreements have been sealed with the UK and Japan. 

But, but, but: there is no deal in place with India. No human trials have been held here—which is a precondition for any Covid vaccine distributed in India. And no manufacturing partner has yet been identified—unlike the Oxford vaccine which has a partnership with Serum Institute of India.

The bottomline: The news of Pfizer is indeed encouraging, but it also reveals an unpleasant truth: A winning vaccine may not be a big win for all of us, equally.

Reading list

Stat News has the best overview. Quartz has a must-read on the definition of ‘effective’. MIT Technology Review outlines the challenges posed by the Pfizer vaccine. Or read New York Times (via ET) on the specific challenge of vaccines that require sub-freezing storage. Mint explains which countries have cornered the Pfizer vaccine in advance. Fast Company reports on the mRNA vaccine—also being developed by Moderna. We did a detailed explainer on the many challenges of actually delivering the vaccine—which go far beyond cold storage facilities.