Moderna vaccine: What it is composed of, how it works and what trials showed

On Monday, US stock markets went soaring on the back of promising results from a vaccine against novelcoronavirusdisease (Covid-19) developed by US pharmaceutical company Moderna. A look at the mRNA-1273 vaccine and how so much hope has been pinned on it:

What is mRNA-1273?

It is the working name of Moderna’s vaccine, which is currently in Phase 1 clinical trials under the aegis of the US National Institute of Allergy and Infectious Diseases (NIAID), a part of the US National Institutes of Health (NIH) and led by Dr Anthony Fauci. The mRNA in the name means messenger RNA, which carries the genetic formula for the coding of a specific protein. In this vaccine, the particular mRNA used codes for the most distinguishing feature of the SARS-CoV2 — the spike protein — which is also the appendage that the virus uses to enter the cell and replicate.

The vaccine, when injected into a person, codes for the spike protein. Thus even without the introduction of an attenuated (recognisable but not harmful) virus into the body, the body learns what the virus looks like and arms itself with the antibodies that are required to act against it.

What are the promising results?

Moderna has announced that the mRNA, on entering the body, had managed to show a degree of immune response in the first eight patients. Tal Zaks, Moderna chief medical officer, told The Financial Times that the results showed that even lower doses elicited an “immune response of the magnitude caused by natural infection”. “These data substantiate our belief that mRNA-1273 has the potential to prevent Covid-19 disease,” he said. Among the side-effects that were noted were chills and a little redness in the place where the injection had been given.

The participants received two doses of the vaccine; different doses were used to test the potency of the vaccine. Two weeks after the second dose, even those on the lowest dose showed enough antibodies to raise hopes of being able to thwart an infection. It was the same level of protection that people who have recovered from the infection show. The group that got a higher dose had higher levels.

Are these the final results of the trial before the vaccine is available?

Far from it. The trials were kicked off on March 16 when the first participant was enrolled, and the results Moderna is currently citing are only from eight patients. This is what the NIH statement said that day: “The open-label trial will enroll 45 healthy adult volunteers ages 18 to 55 years over approximately 6 weeks. The first participant received the investigational vaccine today.”

While the initial results have raised hope, it is important to understand that the actual vaccine may still be some time away and then there are manufacturing capacity issues to deal with before the entire world can realistically hope to benefit from it.

What is next, then?

On May 7, the company announced that it has received regulatory clearance for the Phase II trial that would involve a much larger sample size. “The imminent Phase 2 study start is a crucial step forward as we continue to advance the clinical development of mRNA-1273, our vaccine candidate against SARS-CoV-2. With the goal of starting the mRNA-1273 pivotal Phase 3 study early this summer, Moderna is now preparing to potentially have its first BLA approved as soon as 2021. We are accelerating manufacturing scale-up and our partnership with Lonza puts us in a position to make and distribute as many vaccine doses of mRNA-1273 as possible, should it prove to be safe and effective,” said Stéphane Bancel, Moderna’s Chief Executive Officer.

He added: “We also are continuing to progress our development pipeline and invest in our future. We are very pleased with Vertex’s decision, based on our preclinical progress, to extend our strategic collaboration working to develop the technology to allow for delivery of mRNA in the lung.”