Pfizer vs. Moderna COVID Vaccine - How are they different?

Quick Digest

• The COVID vaccines produced by Pfizer and Moderna were been granted emergency use authorization in the United States.
• The Moderna and Pfizer vaccines both require two doses, are made with mRNA technology, and have shown to be over 94% effective in preventing COVID-19.
• In this article, we will cover some important differences between the vaccines, including as storage requirements, time between doses, and age requirement for vaccination.

Age Eligibility to Receive COVID Vaccine is Different

Pfizer's vaccine is currently approved for individuals over the age of 16, while Moderna's vaccine is approved for individuals over the age of 18. Moderna plans to test its vaccine on 3,000 children ages 12-17. Once there is reliable data from this trial, vaccine eligibility may be expanded to children. 

Vaccine Efficacy is Similar 

Overall effectiveness: Pfizer’s phase three clinical trial included 43,000 participants, half of which got the vaccine. There were 162 cases of COVID-19 in the placebo group and 8 in the vaccine group. Therefore, the vaccine was 95% effective in protecting against COVID-19. 

Moderna’s phase three clinical trial included 30,000 participants, half of which got the vaccine. There were 185 cases of COVID-19 in the placebo group and 11 in the vaccine group. Therefore, Moderna announced that its vaccine was 94.1% effective in protecting against COVID-19. 

Older adults: Pfizer’s vaccine was 93.7% effective in people aged 57 and above. Moderna’s vaccine was 100% effective in people aged 65 and above. 

People with pre-existing conditions: Both Moderna and Pfizer vaccines were tested on people with pre-existing conditions, such as diabetes, lung disease, heart disease, HIV and obesity. Moderna’s vaccine was 95.9% effective in this group and Pfizer’s vaccine was 95.3% effective. 

Men vs women: Both vaccines were about 95% effective in men and a little over 93% effective in women.

Both Vaccines Made With mRNA

Both Pfizer and Moderna created vaccines that use genetic material from the virus, or mRNA (messenger RNA). mRNA vaccines give instructions for our cells to make a spike protein. That protein is recognized by our immune system, which triggers an innate immune response and the production of antibodies. 

mRNA vaccines do not affect our DNA at all; in fact, they do not even enter the nucleus of our cells, which is where our DNA is stored. The structure of the mRNA molecules used in the Pfizer and Moderna vaccines are different. That’s why the vaccines require different storage temperatures. 

Moderna's Vaccine Can Be Stored at Warmer Temperatures 

Due to the mRNA technology used in the vaccines, they must be stored at specific temperatures. Pfizer’s vaccine must be stored at -94 degrees Fahrenheit, which is much colder than a regular freezer temperature.  As a result, this vaccine must be transported using special storage and dry ice to maintain the necessary temperature. At 25 degrees Fahrenheit, the Pfizer vaccine can last 5 days. 

Moderna’s vaccine must be stored at -4 degrees Fahrenheit, which is about the temperature of a normal freezer. At 25 degrees Fahrenheit, the Moderna vaccine can last 1 month. Because the Moderna vaccine can be stored at warmer temperatures, it may be a better option for more rural areas of the country.