A vaccine is administered to an older woman

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What you need to know about the Johnson & Johnson vaccine

The FDA confirmed Emergency Use Authorization after reviewing the safety and efficacy of Johnson & Johnson's vaccine. Here's what you need to know.

On Sunday, the U.S. Food and Drug Administration issued emergency use authorization for a vaccine developed by pharmaceuticals and consumer goods company, Johnson & Johnson, ushering in a third vaccine option for the fight against COVID-19.

Manufactured by Janssen, the pharmaceuticals arm of the J&J brand, the vaccine has been authorized for individuals over the age of 18. In a randomized, placebo-controlled study of the vaccine, the most common side effects were pain at the injection site, headache, fatigue, muscle aches, and nausea.

For more information about the new vaccine, the Expert Insights website of the Johns Hopkins Bloomberg School of Public Health spoke with Joshua Sharfstein, vice dean for public health practice and community engagement, and Andrew Pekosz, professor of molecular microbiology and immunology. Here's what you need to know.

It's a different kind of COVID-19 vaccine

The Johnson & Johnson vaccine is a nonreplicating viral vector vaccine, a method with decades of research behind it. This vaccine uses adenovirus, a common cold virus that, when modified, is able to enter cells but can't make new virus particles. Researchers add the gene for the coronavirus spike protein—the protein on the surface of SARS-CoV-2—to this modified adenovirus. When injected into a person's arm, the adenovirus carries this genetic material into human cells and trains the immune system to react against the coronavirus.

It's more durable and requires just one dose

Unlike mRNA vaccines, which must be stored at -20 degrees Celsius, adenovirus vaccines can be refrigerated for up to three months at 36–46 degrees Fahrenheit. That means it can be distributed more easily in doctor's offices, pharmacies, clinics, or anywhere else. This vaccine promotes a robust immune response after just one dose.

It's important to keep two things in mind

The J&J vaccine is 66% effective while the Pfizer and Moderna shots are as high as 95% effective. The J&J vaccine appears to be even more effective against serious illness than it is against moderate COVID-19. The flu vaccine, which prevents hundreds of thousands of deaths and serious illnesses every year, is about 40%–60% effective. When COVID-19 vaccines were being developed, it was hoped that they would be at least 50% effective. Pfizer's and Moderna's vaccines vastly exceeded all expectations for a good working vaccine, and the J&J also appears to be quite effective.

Some people may prefer the one-shot regimen of the J&J vaccine, given the high levels of protection against serious illness. This vaccine provides a substantial amount of protection against COVID-19, is safe, and its broad use will hasten the decline in COVID-19 cases. That's why many public health departments will use it with multiple populations to be vaccinated.

This article originally appeared on the Expert Insights website of the Johns Hopkins Bloomberg School of Public Health.