The Newly authorized Moderna COVID-19 vaccine VS The Pfizer



Since the start of the pandemic, scientists from all over the world have rallied and pulled all of their resources in order to win the ultimate race of the covid-19 vaccine. Almost a year later, two of these vaccines reached the winning line, albeit both of them only got authorized due to the emergency of the situation in the USA. However, what is the difference between the Moderna vaccine and Pfizer? 

Protection from covid-19 severe symptoms

Both of the vaccines proved to be quite successful in protecting the participants from the virus’s symptoms. Due to their high efficiency during the clinical trials, the United States authorized the emergency usage on December 11 for Pfizer and on 18 December for the Moderna’s vaccine. 

Data revealed that during the third phase of the trials for the Moderna vaccine, the vaccine proved to be  94.1 percent effective at preventing covid-19’s 19 symptoms. In a similar trial, Pfizer’s vaccine proved to be 95 percent effective. The trials for the Pfizer’s were undertaken by groups ranging from 16 to 89 years old, while the age group for the Moderna was 18 to 64 years old.  However, in groups of people older than 65, the Moderna had a lower efficacy of 86.4 percent. 

According to Susanna Naggie, an infectious disease physician at Duke University, the similarity of the results isn’t surprising because they are “a lot more alike than they are different.” She also added that she “ think that’s why we are seeing a very similar profile in terms of the early efficacy data”. 

Better protection after only one dose

Though both vaccines revealed great and promising results, patients need to have two doses to receive the best protection. However, out of the two vaccines, data reveals that the Moderna might be better at fending off symptoms as early as two weeks after the first dose.  During the trial phase of Pfizer, scientists gave the vaccine an efficacy rate of 52.4% after testing the first dose. On the other hand, Moderna’s had an efficacy of 80.2 percent after the first dose and during a similar process.

However, it is important to note that the Moderna vaccine first dose trials included a smaller number of participants than that of Pfizer’s.

Stopping infection vs preventing symptoms

Perhaps one of the most essential distinctions between the two vaccines is whether they can stop infection while preventing symptoms. Early data shows that the Moderna vaccine might be able to protect from asymptomatic infections along with symptomatic disease. Thus, unlike Pfizer’s, Moderna’s ability to stop infections will help to curb the coronavirus’ spread and build immunity in communities.  

On the other hand, though Pfizer hasn’t revealed any data announcing similar action, many believe that the vaccine applies a similar process. “I don’t think there’s any reason to believe that there will be a difference between the two,” Naggie says.

Side effects

Though the dice are still rolling on whether any of the vaccines can cause a serious allergic reaction, both of them seem to have very similar other side effects. They both induce pain after the injection, “it pretty universally causes arm pain,” Cox says. Additionally, both seem to cause symptoms like fatigue, chills, body aches, or headache. 

However, trials show that  Moderna’s vaccine has higher symptoms than Pfizer’s. Such symptoms include tenderness, swelling as well as the other mentioned before. In any case, experts agree that these symptoms are a natural response after receiving any vaccine. “In fact, it shows that your body is developing a robust immune response, which is exactly what you want,” Naggie stated.

Furthermore, in both trials, some isolated cases experienced a temporary weakness or paralysis of facial muscles. Nonetheless, those cases are still rare overall in both arms of the trials.

Should people take more than one type of COVID-19 vaccine?

All the similarity, as well as the confusion and terror regarding the covid-19, does pose the above question.  Florian Krammer, professor of vaccinology at Icahn School of Medicine at Mount Sinai in New York City, admits that it “isn’t a ridiculous question at all. We do this all the time in research. We use different vaccine platforms because, sometimes, we get interesting results.”

However, due to the very limited data scientists have on the covid-19 and the vaccines, the result might end up being counterproductive. In theory, a combination might prove to be greatly beneficial, but in reality, many factors can easily clash together. “I don’t think we have nearly enough information that people should start mixing and matching COVID-19 vaccines,” says Angela Rasmussen, a virologist at the Center for Global Health Science.


Johnson, C. A. Y. S. (2020, December 22). Your questions about coronavirus vaccines. Washington Post., K. (2020, December 18). How the Moderna and Pfizer COVID-19 vaccines compare. Los Angeles Times. people take more than one type of COVID-19 vaccine? (2020, December 19). Science., H. (2020, December 19). How does the newly authorized Moderna COVID-19 vaccine compare to Pfizer’s? Science News.


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