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Explained: Why Moderna’s Covid-19 vaccine scores over Pfizer’s jab, and why it could be a compelling option for India

Moderna’s vaccine remains stable for 30 days when refrigerated at 2-8 degrees Celsius and is stable for 12 hours at room temperature. For longer-term storage and shipping, it needs to be kept at minus 20 degrees Celsius, a temperature that distributors can deal with. The Pfizer-BioNTech vaccine has to be stored at about minus 70 degrees Celsius, requiring ultra-cold storage.

November 18, 2020 / 10:13 AM IST

US biotech company Moderna on Monday announced that the first interim analysis of its Covid-19 vaccine demonstrated 94.5 percent efficacy. Moderna said the trial has met the statistical criteria pre-specified in the study protocol. The company intends to submit an Emergency Use Authorization (EUA) application with the USFDA in the coming weeks.

Moderna’s announcement came one week after Pfizer and BioNTech said that their vaccine was more than 90 percent effective. The early positive data for the Pfizer and Moderna vaccines has validated the mRNA platform, on which the vaccines have been developed.

While the news led to Moderna’s shares rising almost 10 percent on the NASDAQ on November 16, Pfizer’s shares dropped 3.34 percent on NYSE, and its German partner BioNTech’s ADRs fell by 13.66 percent on the NASDAQ. This was largely because Moderna’s vaccine is perceived to have an edge over other candidates on various parameters, particularly storage and temperature.

Here is an explainer comparing both vaccines:

Moderna vs Pfizer data


COVID-19 Vaccine

Frequently Asked Questions

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How does a vaccine work?

A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.

How many types of vaccines are there?

There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.

What does it take to develop a vaccine of this kind?

Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.

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Moderna’s first interim analysis was based on 95 cases, of which 90 Covid-19 cases were observed in the placebo group versus five in the vaccine group, resulting in a point estimate vaccine efficacy of 94.5 percent.

A secondary endpoint analysed severe cases of Covid-19. There were 11 severe cases in this first interim analysis. All 11 cases occurred in the placebo group and there were no cases in the vaccinated group.

ALSO READ: Moneycontrol's COVID-19 Vaccine Tracker here.

The preliminary analysis suggests a broadly consistent safety and efficacy profile across all evaluated subgroups.

In contrast, Pfizer’s interim analysis evaluated 94 confirmed cases of Covid-19 in clinical trial participants. The cases were split between vaccinated individuals and those who received a placebo. Pfizer said the vaccine data indicated an efficacy rate above 90 percent, just seven days after the second dose.

Pfizer did not disclose how many of the confirmed cases had received the vaccine and how many got the placebo. Moderna’s vaccine fared slightly better than Pfizer.

Why the trial design is interesting

Moderna’s Phase 3 trial is a randomised, 1:1 placebo-controlled study testing the vaccine on 30,000 participants, ages 18 and older, in the US.

The company completed enrolment on October 22. About 42 percent of the participants are medically high-risk groups, which means that they are above 65 years and people with comorbidities.

Pfizer’s phase-3 study enrolled 43,538 participants, but it doesn’t give any break-up of the percentage of medically high-risk groups.

Both Moderna and Pfizer said they have taken a lot of care in ensuring racial diversity in enrolment of participants. Moderna said its study includes more than 11,000 participants from communities of colour, representing 37 percent of the study population, which is similar to the diversity of the US at large. This includes more than 6,000 participants who identify as Hispanic, and more than 3,000 participants who identify as Black or African American.

Pfizer said approximately 42 percent of its global participants and 30 percent of US participants have racially and ethnically diverse backgrounds.

Historically, Blacks, Hispanics and Asians are under-represented in clinical research. Having racial and ethnic diversity, helps the vaccine to sail much more easily when other regulators review the data.

Storage and distribution

This is where the Moderna vaccine has a clear edge over the Pfizer-BioNTech vaccine. Moderna says its vaccine will remain stable for 30 days when refrigerated between 2 degrees Celsius and 8 degrees Celsius. The vaccine is also stable for 12 hours at room temperature.

For longer-term storage and shipping, the vaccine needs to be kept at freezer temperatures of minus 20 degrees Celsius, a temperature that distributors can deal with.

In contrast the Pfizer-BioNTech vaccine must be stored at about minus 70 degrees Celsius, requiring ultra-cold storage. In other words, the vaccine has to be kept cooler than the lowest temperature in Antarctica.

This vaccine can be moved to a refrigerator, but only for five days. This becomes a logistical nightmare even for advanced countries with vast cold storage infrastructure.  Pfizer has to find a fix for the problem of cold storage.


Both the Pfizer and Moderna vaccines have to be given in two doses. Pfizer said it expects to globally produce up to 50 million vaccine doses in 2020 and up to 1.3 billion doses in 2021. Pfizer, given its vast manufacturing infrastructure and experience, can easily ramp up production.

Moderna said it is on track to have about 20 million doses of its vaccine ready to ship in the US by the end of the year. It is expecting to be able to produce 500 million to 1 billion doses next year.

India availability

Moderna has not announced any plans to roll out the vaccine in India. It is highly unlikely that the vaccine will be available in India soon.

The company had earlier told Moneycontrol that it is in talks with several countries for a possible rollout of the vaccine.  Moderna said it is committed to “equitable access” to its vaccine candidate but declined comment on a possible plan for a launch in India or a tie-up with Indian companies to distribute the vaccine.

What are analysts saying?

“With both Moderna and Pfizer demonstrating 90 percent-plus efficacy, which is very promising, I suspect the remaining vaccines will mostly land in this efficacy range. So, what will separate them is whether they work as single dose or if they are much easier to administer,” said Davinder Gill, entrepreneur and former CEO of Hilleman Laboratories.

Viswanath Pilla is a business journalist with 14 years of reporting experience. Based in Mumbai, Pilla covers pharma, healthcare and infrastructure sectors for Moneycontrol.
first published: Nov 17, 2020 12:03 pm
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