On Feb. 27, the Food and Drug Administration announced it had issued an emergency use authorization for Johnson & Johnson’s (J&J) one-dose COVID vaccine. But some have questioned whether the J&J vaccine is a "second-best" vaccine, comparing how it performed in clinical trials versus the two-dose messenger RNA vaccines from Moderna and Pfizer. However, the FDA says J&J’s vaccine offers strong protection against what matters most: serious illness, hospitalizations and death. Here's a breakdown of the differences between the available COVID vaccines:
Which COVID vaccine is best?
How effective is each vaccine?
Two doses of the Pfizer and Moderna vaccines were about 95% effective against cases of symptomatic COVID-19. A single shot of the J&J vaccine had a total effectiveness of about 66% against moderate to severe COVID-19 cases. However, all three vaccines offer strong protection against the most serious and life-threatening effects of COVID-19, the symptoms that cause people to die or require mechanical ventilation and treatment in an intensive care unit.
To put things into perspective, flu vaccines typically provide 40% to 60% effectiveness, according to the U.S. Centers for Disease Control and Prevention. So to get to 95%, even 66% efficacy, is impressive.
Further, the Johnson & Johnson vaccine is proven effective against the new South African COVID-19 variant, because part of its clinical trial was conducted in that country and in Latin America. The Moderna and Pfizer vaccines were only tested against the original strain of COVID-19, and the new variants are posing some limited challenge to the protection those vaccines confer.
How are they different?
The Pfizer-BioNTech and Moderna vaccines differ from traditional vaccines in their use of mRNA. Instead of introducing a weakened or an inactivated germ into your body, this vaccine injects mRNA, the genetic material that our cells read to make proteins, into your upper arm muscle. It teaches your body how to make the protein that triggers antibody production so if the real virus later enters your body, your immune system will recognize it, according to the federal Centers for Disease Control and Prevention.But mRNA is very fragile, so the vaccine must be kept frozen until right before it's administered.
The J&J vaccine is a viral vector vaccine. This means it uses a modified version of a different virus (the vector) to deliver important instructions to our cells. For COVID-19 viral vector vaccines, the vector (notthe virus that causes COVID-19, but a different, harmless virus) will enter a cell in our body and then use the cell’s machinery to producea harmless piece of the virus that causes COVID-19. This piece is known as a spike protein and it is only found on the surface of the virus that causes COVID-19.
This type of vaccine only needs to be kept refrigerated, not frozen, making it easier to transport and store. The J&J vaccine also only requires a single dose for effective protection, making it much easier to vaccinate larger numbers of people. None of the three COVID vaccines affect or interact with our DNA in any way.
What are the side effects of each vaccine?
Like Pfizer and Moderna's COVID-19 vaccines,the main side effects of the J&J shot are pain at the injection site and flu-like fever, fatigue and headache. However, there have been fewer cases of severe allergic reactions, called anaphylaxis, to the J&J vaccine compared with the Moderna and Pfizer vaccines.
Can I choose which vaccine I get?
It's going to be rare for some weeks to come that a person will have a choice between the three vaccines. According to the CDC, all three vaccines are safe and effective, and the best one is the one you can get a hold of first. There is no evidence that shows reason to favor one vaccine over another.
The bottom line is that all three vaccines; Moderna, Pfizer and J&J, will prevent you from getting severely sick or dying from COVID-19. As supplies become more readily available to the general public, it's important to take whichever vaccine is available to you- don't wait for an alternative.
Want more information about COVID-19? Visit our resources page.