Everything You Need to Know about the Johnson & Johnson COVID -19 Vaccine

Women with sanitation gear

A third vaccine has entered the scene. On February 28, the Johnson & Johnson vaccine received approval from the FDA for an emergency use authorization. That means they passed all the safety requirements to provide people in the U.S. with their vaccine. 

You’ve probably already heard of the other two vaccines developed by Pfizer and Moderna, and you might be wondering if there are any differences between the vaccines. There are a few key differences and we’ll go over what you need to know about the Johnson & Johnson vaccine, and how it compares to the other two. 

What to know about Johnson & Johnson’s COVID-19 Vaccine

The Johnson & Johnson vaccine is also referred to as the Janssen vaccine. This is because Janssen Pharmaceutica, a Belgium-based division of Johnson & Johnson, developed the vaccine in collaboration with Beth Israel Deaconess Medical Center.

The COVID-19 vaccine from Johnson & Johnson was developed with a weakened virus called adenovirus, a common cause of respiratory infections like the cold or flu. The DNA in the adenovirus is modified so that it produces a key part of the SARS-CoV-2 virus particle which then triggers your body to produce an immune response against it. The adenovirus that delivers the SARS-CoV-2 DNA particle cannot multiply, so it does not cause infection. 

Because this system is based on stable DNA molecules, it does not require ultra-cold storage, making it easier to distribute.

Studies showed that only 9% of volunteers experienced fever. Volunteers have also not developed a severe allergic reaction, or side affect. The vaccine did not appear to cause any excess serious complications.

Johnson & Johnson plans to have 20 million doses of its vaccine available by the end of March. It will also deliver 100 million shots around the U.S. in the first half of 2021.

Comparing Johnson & Johnson Vaccine to Moderna and Pfizer

There are some key differences between the three vaccines. Despite differences, doctors advise to take the first available option.

Vaccine Types

  • Johnson & Johnson: Uses existing technology that involves adenovirus. 
  • Moderna and Pfizer: Uses mRNA technology to build immunity. 

Required Shots

  • Johnson & Johnson: The first single-dose vaccine.
  • Moderna: Requires two doses 28 days apart.
  • Pfizer: Requires two doses 21 days apart. 

Storage Requirements

The new Johnson & Johnson vaccine plays an important role in vaccinating rural and underserved areas since storage is much easier.

  • Johnson & Johnson: Can be kept in a standard refrigerator. 
  • Moderna and Pfizer: Has to be kept between -112ºF to ‑76ºF. 


It’s hard to compare the J&J vaccine to Moderna and Pfizer because the trials were testing for different outcomes. During J&J’s Phase 3 trials, they tested if one dose of their vaccine was strong enough to protect against moderate to severe Covid illness- starting at 14 or 28 days after the shot. They also included other variants of Covid that have emerged. 

Moderna and Pfizer did not test any other Covid variants (they were not around when the trials started) and were testing for any symptomatic Covid infection. Moderna counted effectiveness 14 days after the second shot, and Pfizer counted seven days after the second shot. 

  • Johnson & Johnson: The J&J one-dose vaccine was shown to be 66% protective against moderate to severe Covid infections. But the vaccine was shown to be 85% protective against severe disease.
  • Moderna: The Moderna vaccine is 94.1% effective at preventing symptomatic Covid-19 after the second dose.
  • Pfizer: The Pfizer vaccine is 95% effective at preventing symptomatic Covid infection after two doses.

Age Requirements

  • Johnson & Johnson: Required to be 18 and older. 
  • Moderna: Required to be 18 or older but the company is currently testing its vaccine in 12 to 17-year-olds. 
  • Pfizer: Required to be 16 or older. 

Side Effects

The more intense side effects associated with the second doses of the Pfizer and Moderna vaccines are not a concern with J&J’s vaccine, as the new vaccine only requires one shot.

  • Johnson & Johnson: Soreness and swelling on the arm you got the shot, fatigue, body aches, tiredness, fever or chills.
  • Pfizer and Moderna: All the same as J&J, plus reports of severe allergic reaction (anaphylaxis) has been reported. 

In the end, all three vaccines appear to do what they’re intended to, which is prevent severe complications, hospitalization and death due to the coronavirus.