What are the differences between the COVID-19 vaccines?

COVID-19 Vaccine Comparison

Manufacturer Pfizer, Inc. Moderna TX, Inc. Johnson & Johnson
Vaccine Name Pfizer-BioNTech COVID-19 Vaccine mRNA-1273 JNJ-78436735
Storage Temperature -112˚ to -76˚ F -4˚ F 36˚ to 46˚ F
Delivery Method RNA (mRNA) by lipid particles RNA (mRNA) by lipid particles DNA by non-replicating adenovirus
Ages Authorized 6 months + 6 months + 18+
Contains Live Virus? No No Yes, non-infectious
Effectiveness 95% (Estimated) 94% (Estimated) 66% Overall
See the vaccine distribution schedule.

Learn about each COVID-19 vaccine and how they are similar:

The Pfizer, Moderna and Johnson & Johnson COVID-19 vaccines are being distributed across the country. But the FDA is also reviewing other vaccines for safety and efficacy. Find out the differences between them.

Pfizer Vaccine

The Pfizer vaccine is available to those 6 months and older. It is a 2-shot series with a third dose recommended for those 6 months to 5-years-old. A third dose is recommended for those with certain immunocompromising conditions, and a booster dose is also recommended. Learn more about booster doses. This vaccine consists of genetic material called mRNA that stimulates the immune system to make antibodies that protect against COVID-19.

Why more than one Shot? More than one dose helps your immune system figure out how to stop a future COVID-19 infection.

The vaccine material breaks down shortly after it’s taken into our cells and does not impact our genes. This vaccine is new but RNA vaccines are not. They have been studied for several years and used against influenza, Ebola and the Zika virus.

This vaccine needs to be stored in extremely cold temperatures, between -112 degrees Fahrenheit and -76 degrees Fahrenheit, until its ready for use. This ensures the vaccine remains stable. The first vaccine acquired by Yale New Haven Health was the Pfizer vaccine and we have the necessary storage to keep it at the appropriate temperatures.

The Pfizer vaccine is about 53% effective after the first dose and 95% effective after the second dose, which is why it’s so important for all recipients to take both doses. The third dose or booster brings up the recipient's level of immunity. 

Common side effects include pain at the injection site, fever, fatigue, muscle pain and joint pain. Some of those mild side effects can occur after getting the flu shot.

Moderna Vaccine

The Moderna vaccine is available for those 6 months and older. Like the Pfizer vaccine, it is a mRNA vaccine and consists of 2 injections and a third dose is also recommended for certain individuals who are immunocompromised. A booster is also recommended. Neither the Moderna or Pfizer vaccine contains any live or dead virus, so you can’t get COVID-19 from them.

There are, however, some slight differences. The Moderna vaccine requires storage at -4 degrees Fahrenheit, but is stable at room temperature for a slightly longer period of time than the Pfizer vaccine.

Common side effects can include pain at the injection site, fever and fatigue. The Moderna vaccine is around 94% effective after both doses.

Synthetic Messenger RNA (mRNA) tricks your body into producing some of the vital proteins so it can produce a defensive response to them. Once injected with Double-Stranded DNA vaccines, our bodies make antibodies to defend against infection.

Find out how vaccines work

Johnson & Johnson

Johnson & Johnson has received the FDA Emergency Use Authorization for its vaccine. It works by using a modified adenovirus to enter cells, allowing the body to create antibodies. This technology has been used in the past to fight Ebola, HIV and Zika. Like the other COVID-19 vaccines, it does not alter your DNA or give you the virus.

One big difference between this vaccine and the other well-known vaccines is that it only requires one dose. A booster is recommended for adults 18 and older. Johnson & Johnson found it was 72% effective in the U.S. and 66% effective overall in preventing moderate to severe cases, 28 days after vaccination. It also does not require the ultra-cold temperatures needed for the mRNA vaccines. It is stable for at least three months at 2-8 degrees Celsius, or around 36 to 46 degrees Fahrenheit.

AstraZeneca Vaccine

The AstraZeneca vaccine is based on a different technology than the Moderna and Pfizer vaccines. It is made from a weakened version of a common cold virus (known as an adenovirus) from chimpanzees. It has been modified to look more like coronavirus - although it can't cause illness in humans.

When the vaccine is injected into a patient, it prompts the immune system to start making antibodies and primes it to attack any coronavirus infection. Something that sets this vaccine apart from the mRNA vaccines is that it appears to be very stable at relatively normal, refrigerated temperatures and it is about 63% effective against infection.

It has not yet been approved for emergency use by the FDA in the U.S. 

How are these vaccines similar?

All of the vaccines developed in response to the pandemic were initially studied using adult participants, although studies have since expanded. While these vaccines continue to be studied, millions of people have safely gotten vaccinated.

Any time a vaccine is approved for emergency use, they will continue to be studied and monitored for safety by the FDA. It's important to note that all of the vaccines approved by the FDA help to protect against severe cases of COVID-19 and death. If patients are eligible to get a vaccine appointment, Yale New Haven Health does not recommend waiting for access to one particular vaccine based on their efficacy. The best way to protect yourself is to get vaccinated, regardless of the manufacturer. 

Learn more about COVID-19 vaccines