How J&J vaccine compares to Pfizer, Moderna shots

Infectious disease specialist says any of those 3 vaccines will prevent severe COVID-19

The U.S. now has a third vaccine to prevent COVID-19, as the Food and Drug Administration on Saturday cleared a Johnson & Johnson shot that works with just one dose instead of two.

The Pfizer and Moderna COVID-19 vaccines require two doses, and health experts have anxiously awaited a one-and-done option to help speed vaccinations.

The J&J vaccine is also easier to handle, lasting three months in the refrigerator compared to the Pfizer and Moderna options, which must be frozen.

“It means a lot. More people can get vaccinated against this deadly virus,” infectious disease specialist Dr. Mohammed Reza told News4Jax on Sunday. “It means the vaccine can travel and vaccinate people in distant locations that don’t have cold refrigerators available. This vaccine can be stored at regular refrigerator temperature for up to three months.”

All COVID-19 vaccines train the body to recognize the new coronavirus, usually by spotting the spikey protein that coats it. But they’re made in very different ways.

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, and similar to COVID-19 vaccines made by AstraZeneca and China’s CanSino Biologics.

“It’s using a very harmless virus called an adenovirus, only a piece of that, and it is inserted into the little portion of the spike protein from the virus itself, the coronavirus, so that’s injected into the patient, and the patient makes those spike proteins,” Reza said. “It’s almost like we’re giving your body a recipe and it’s being given to the patient. People who get injected with that vaccine make that spike protein, which stimulates our immune system to make antibodies against this virus.”

The Pfizer and Moderna vaccines are made with a different technology, a piece of genetic code called messenger RNA that spurs cells to make those harmless spike copies.

“I am excited about the messenger RNA technology, because if you look at how quickly you can turn around and make vaccines, it is pretty amazing. This will help us fight other viruses,” Reza said. “It’s monumental in terms how science will move forward and how it will produce vaccines.”

In the U.S., the two-dose Pfizer and Moderna shots were 95% protective against symptomatic COVID-19. J&J’s one-dose effectiveness of 85% against severe COVID-19 dropped to 66% when moderate cases were rolled in. But there’s no apples-to-apples comparison because of differences in when and where each company conducted its studies, with the Pfizer and Moderna research finished before concerning variants began spreading.

“It is quite effective,” Reza said of the J&J vaccine. “It is 66% effective across the world, preventing severe COVID infection. In the US, it is 72% effective in preventing severe COVID infection.”

Reza said any of the three vaccines available in the U.S. will prevent severe COVID-19.

“As a population, as people, our backs are against the wall. You want that protection against the deadly virus and the different variants we are seeing,” Reza said. “This is a race against time in terms of getting vaccinated.”


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