Moderna’s Covid Vaccine Interim Analysis Shows A 94.5 Percent Effectiveness

 Andreas Prott/

More positive news in the search for a Covid-19 vaccine. US biotech firm Moderna has reported encouraging findings from the phase 3 trial of its candidate vaccine. An interim analysis shows that its jab has an efficacy of around 94.5 percent. This value could change when the final data is submitted to the U.S. Food and Drug Administration (FDA) for review and approval.

While the data is not peer-reviewed yet and there is still a lot more worked to be done, this announcement together with the ones from last week has been welcomed with excitement. The trial involved 30,000 people in the US. Half of the participants were given two doses of the vaccine (four weeks apart) while the rest were given a placebo.

The estimate of the efficacy is based on the number of Covid-19 cases that have been reported during the trial. 95 participants caught Covid-19 while being on the trial, with 90 being on the placebo and 5 on the vaccine. 11 people had severe Covid-19 but none of these were among those immunized.

“This is a pivotal moment in the development of our COVID-19 vaccine candidate. Since early January, we have chased this virus with the intent to protect as many people around the world as possible. All along, we have known that each day matters. This positive interim analysis from our Phase 3 study has given us the first clinical validation that our vaccine can prevent COVID-19 disease, including severe disease,” Stéphane Bancel, Chief Executive Officer of Moderna, said in a statement

“This milestone is only possible because of the hard work and sacrifices of so many. I want to thank the thousands of participants in our Phase 1, Phase 2 and Phase 3 studies, and the staff at our clinical trial sites who have been on the front lines of the fight against the virus. They are an inspiration to us all.”

A question on people's minds is the safety of these vaccines. The company believes that the vaccine is well tolerated and there are no reports of significant side effects. A small fraction of people experiences some severe but short-lived side-effects such as fatigue, headaches, muscle pain, as well as pain and redness around the injection site. This is expected from such a vaccine and it is on par with the types of side-effects one might experience with the flu vaccine.

The vaccine is also an RNA vaccine like the one developed by Pfizer and BioNTech whose interim results were announced last week. It works by injecting in the human body a small fragment of the virus's genetic code. This piece of mRNA is used by the virus, SARS-CoV-2, to create its external spike proteins. This is a key protein used by the virus to infect cells.

The vaccine stimulates human cells to produce this protein (without the danger of having the virus attached) and our immune system gets a chance to recognize the proteins as a foreign object and learn how to get rid of it. If all works, then our immune cells can recognize the proteins whenever. So if our body gets infected by SARS-CoV-2, they can quickly defeat it.

Pfizer vaccine requires ultra-cold storage ( -75 °C/ -103 °F), but it can be kept in the fridge for five days. Moderna’s one instead has to be stored at a deep freezer temperature (-20 °C/ -4 °F) but can be kept in a regular fridge for up to 6 months.


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