With three coronavirus vaccines now approved in the U.S., what is the difference between the vaccines and should you opt for one over the other?
According to medical experts, the three vaccines currently available in the U.S. each offer some level of protection, and you should get whatever one is made available to you as soon as you can.
Pfizer and Moderna COVID vaccines have been circulating across the U.S. the longest, both requiring two shots for full protection.
Meanwhile, the Johnson & Johnson’s single-dose vaccine also offers strong protection against severe COVID-19, according to an analysis by U.S. regulators.
One thing is clear from medical experts: Get whatever vaccine is made available to you.
"All three of them are really quite good, and people should take the one that's most available to them," Dr. Anthony Fauci said in a late February appearance on "Meet the Press."
"If you go to a place and you have J&J and that's the one that's available now, I would take it. I personally would do the same thing," he said. "I think people need to get vaccinated as quickly and as expeditiously as possible," he said."
Here's what to know:
How effective is each vaccine?
The FDA said J&J’s vaccine offers strong protection against what matters most: serious illness, hospitalizations and death. One dose was 85% protective against the most severe COVID-19 illness, in a massive study that spanned three continents — protection that remained strong even in countries such as South Africa, where the variants of most concern are spreading.
Published results from a mass vaccination campaign in Israel showed Pfizer's vaccine was 92% effective at preventing severe disease after two shots and 62% after one. Its estimated effectiveness for preventing death was 72% two to three weeks after the first shot, a rate that may improve as immunity builds over time. Meanwhile, the Moderna vaccine provides a similar level of protection, 94.1%, and requires two shots, 28 days apart.
It is not known if any of the three vaccines prevent the spread of the virus by people who are asymptomatic.
While the overall effectiveness data may suggest the J&J candidate isn't quite as strong as the two-dose Pfizer and Moderna options, all of the world’s COVID-19 vaccines have been tested differently, making comparisons nearly impossible, CNBC reported.
"If you kind of do a comparison for influenza vaccines, which we do annually, influenza's efficacy can range anywhere from 40% to 60% - and that's a good year," Monica Hendrickson, public health administrator for the Peoria County Health Department said Wednesday. "So again, something that's high public health was, you know, we were hoping for something above 40%. To get to 95%, even 65%, that's a homerun."
Hendrickson noted that the vaccines each hold a high effectiveness against death and severe illness for coronavirus.
"So, really, you're looking at a distinction that from a clinical standpoint, or from, you know, an epidemiological standpoint is very minor compared to what we really are hoping for, which is decreases in death and decreases in severe illness, where they all match up between the three vaccines," Hendrickson said. "Most important thing though is that when these vaccines come on the market, if you have an option to any of these, get one of them."
Hendrickson's message echoes one made by Dr. Marina Del Rios, emergency medicine specialist at the University of Illinois-Chicago, during NBC Chicago's "Vaccinated State" panel recently.
“Part of my messaging in the community has been that the vaccines on the market are equally efficacious and equally safe," Del Rios said. "The best vaccine you can get is the one that you can get a hold of first, and getting vaccinated earlier, sooner rather than later, protects us from getting sick ourselves and also our community, which has been so terribly devastated by this virus.”
Dr. Arnold Monto of the University of Michigan, who chaired an FDA advisory panel that unanimously voted that the Johnson & Johnson vaccine’s benefits outweigh its risks, said the evidence shows no reason to favor one vaccine over another.
"What people I think are mostly interested in is, is it going to keep me from getting really sick?" Collins said. "Will it keep me from dying from this terrible disease? The good news is all of these say yes to that."
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.
The Johnson & Johnson and the AstraZeneca vaccines also rely on instructions for creating the spike protein that gives the coronavirus its distinctive shape and which it uses to enter a cell. But they make use of DNA inside an adenovirus, a common virus.
J&J’s shot uses a cold virus like a Trojan horse to carry the spike gene into the body, where cells make harmless copies of the protein to prime the immune system in case the real virus comes along. It’s the same technology the company used in making an Ebola vaccine.
The Pfizer and Moderna vaccines must also be kept frozen, while the J&J shot can last three months in the refrigerator, making it easier to handle. AstraZeneca's vaccine, widely used in Europe, Britain and Israel, is made similarly and also requires refrigeration but takes two doses.
What are the side effects for 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. No study participant experienced the severe allergic reaction, called anaphylaxis, that is a rare risk of some other COVID-19 shots, although one experienced a less serious reaction.
The FDA said there were no serious side effects linked to the vaccine so far, although it recommended further monitoring for blood clots. In the study, those were reported in about 15 vaccine recipients and 10 placebo recipients, not enough of a difference to tell if the vaccine played any role.
Are there other options?
Additional vaccines from AstraZeneca and Novavax could also be potentially approved in the U.S.
On March 22, AstraZeneca announced that findings of a large U.S. trial have shown that its coronavirus vaccine is 79% effective in preventing symptomatic illness and 100% effective against severe disease and hospitalization.
It said it plans to seek emergency use approval from the FDA in early April.
Distribution of the AstraZeneca vaccine was paused briefly in several European countries over concerns it may be linked to blood clots, but the EU's agency that manages prescription drugs later said there was no connection and that the vaccine is safe.
Novavax, which is the lesser known of the remaining vaccines, is also on the horizon.