Johnson & Johnson’s COVID-19 Vaccine Gets Green Light in U.S.

Learn how this vaccine works, how it measures up to Pfizer and Moderna and what happens next.

Updated on February 28, 2021 at 6:15pm EST.

The Johnson & Johnson (J&J) COVID-19 vaccine has cleared it's final hurdle and is now available in the United States.

On Sunday, February 28, Rochelle P. Walensky, MD, MPH, director of the Centers for Disease Control and Prevention (CDC), accepted the agency's Advisory Committee on Immunization Practices' (ACIP) recommendation, which endorsed the safety and effectiveness of the vaccine and its use in people age 18 and older. It's now the third vaccine to receive a green light in the United States. But it's the only vaccine that requires just one dose.

"This vaccine is also another important tool in our toolbox to equitably vaccinate as many people as possible, as quickly as possible," said Dr. Walensky in a February 28 news release.

"I know that many Americans look forward to rolling up their sleeves with confidence as soon as a COVID-19 vaccine is available to them," Walensky added. "Having different types of vaccines available for use, especially ones with different dosing recommendations and storage and handling requirements, can offer more options and flexibility for the public, jurisdictions and vaccine providers. Getting vaccinated with the first vaccine available to you will help protect all of us from COVID-19."

This official CDC recommendation follows Saturday’s decision by the U.S. Food and Drug Administration (FDA) to grant Emergency Use Authorization (EUA) of J&J's vaccine. The FDA concluded the vaccine, which was developed with J&J-owned Janssen Pharmaceuticals, is safe and effective against COVID-19.

Overall, the vaccine was 66 percent effective at preventing moderate to severe disease 28 days after immunization. The most commonly reported side effects included pain at the injection site, headache and muscle aches.

In mid-December, the FDA granted EUA to the COVID-19 vaccine developed by Pfizer and the German drugmaker, BioNTech as well as the vaccine developed by Moderna. Both are mRNA vaccines, which require two shots spaced three weeks apart (Pfizer) or four weeks apart (Moderna).

So, how does it compare to the two mRNA vaccines already being distributed across the United States?

Will it stand up to the more infectious coronavirus variants spreading across the country?

And why it's being touted as a possible game-changer in the fight to end the pandemic once and for all?

Here’s a breakdown.

What the trials showed
J&J announced the first set of complete results from its global Phase 3 trial. It was conducted in eight countries across three continents and included about 40,000 people of different ages, races and ethnicities.

Overall, the vaccine was 66 percent effective against moderate to severe COVID-19 after 28 days. 

It's effectiveness in protecting against moderate to severe infection varied geographically, ranging from 72 percent in the United States to 68 percent in Brazil.

The vaccine was also nearly 82 percent effective against severe disease and 64 percent effective against moderate disease in South Africa where 95 percent of all COVID-19 cases involved in the trial were linked to a more infectious coronavirus variant, known as B1351.

In clinical trials however, the J&J vaccine prevented 100 percent of hospitalizations and deaths. No serious safety concerns were reported. J&J revealed that 9 percent of trial participants developed a fever, but its vaccine was generally well-tolerated.

How it compares to the Pfizer and Moderna vaccines
The efficacy rate of J&J’s vaccine is not as high as Pfizer and Moderna's vaccines, which were shown to be 95 percent and 94.1 percent effective, respectively. But those efficacy rates from clinical trials don't tell the whole story and it's a bit like comparing apples and oranges.

The Pfizer and Moderna clinical trials were conducted before the coronavirus variants emerged. And while researchers have been using laboratory tests to assess how well those who’ve been immunized with these mRNA vaccines are protected from worrisome mutations, the J&J vaccine trials were conducted in South Africa and Brazil where concerning variants have since been identified.

Secondly, both Pfizer and Moderna’s vaccines are mRNA vaccines, which is a newer type of vaccine technology. They work by using mRNA to deliver a piece of genetic material that carries instructions for making the protein that the coronavirus (SARS-CoV-2) uses to infect cells. This triggers an immune response in the body.

The J&J vaccine is not an mRNA vaccine. It’s a non-replicating viral vector vaccine. Rather than using mRNA, it uses a modified version of another type of virus as a vector (or mode of delivery) for genetic material that codes for a piece of the coronavirus in order to trigger a protective immune response.

The viral vector used by the J&J vaccine is a common cold virus called adenovirus 26. But the vaccine does not cause an infection with either this virus or the coronavirus. (And none of these vaccines—Pfizer, Moderna or J&J—enter the nucleus of cells or have the ability to alter a person’s DNA.)

It's important to remember that in J&J’s large clinical trial, 28 days after receiving the vaccine, no one who was immunized was hospitalized or died from COVID. Also, J&J's vaccine has milder side effects than Pfizer and Moderna, according to the FDA. 

Why J&J’s vaccine may be a game-changer
There are three other big differences between the J&J vaccine and the Pfizer and Moderna mRNA vaccines, which could trigger a significant shift in the speed and effectiveness of the vaccine rollout and efforts to halt the spread of COVID-19.

  1. It’s is a single-dose vaccine, promising faster protection.
  2. It requires only standard refrigeration and is stable longer at this temperature range.
  3. J&J expects to produce one billion doses this year.

One dose vs. two
Both the Pfizer vaccine and the Moderna vaccine require two doses. Those who receive the Pfizer vaccine must get a second shot 21 days later. Those who get the Moderna vaccine must get a second shot 28 days later. Both doses are necessary in order for the vaccines to be fully effective.

The J&J vaccine, however, is a one-dose vaccine. This means people only need to get one shot for the vaccine to be effective.

“The potential to significantly reduce the burden of severe disease, by providing an effective and well-tolerated vaccine with just one immunization, is a critical component of the global public health response,” said Paul Stoffels, MD, Vice Chairman of the Executive Committee and Chief Scientific Officer, Johnson & Johnson in a January 29 news release. “A one-shot vaccine is considered by the World Health Organization to be the best option in pandemic settings, enhancing access, distribution and compliance.”

A third vaccine that is a single-dose vaccine has the potential to protect hundreds of millions of people from severe infection or death from COVID-19, Dr. Stoffels says. “It also offers the hope of helping ease the huge burden placed on healthcare systems and communities,” he adds.

Easier storage
The fact that the J&J vaccine relies on a harmless virus to deliver the genetic code for the coronavirus protein that will trigger an immune response means that it can be stored in a normal refrigerator and remain stable for a longer period of time.

The company says its vaccine will remain stable (and effective) for three months at 35-46° F.

Moderna’s vaccine, on the other hand, remains stable for 30 days at 36° to 46°F.

At a colder temperature of -4°F, the J&J vaccine would remain stable for two years and the Moderna vaccine could remain stable for up to six months.

Meanwhile, Pfizer’s vaccine must be stored in an ultra or deep freezer at between -112 and -76° F in order to remain effective. Before mixing, however, the vaccine may be stored in the refrigerator for up to 5 days at between 36 and 46° F, according to the CDC.

Ramping up production
The pandemic has resulted in an unprecedented and historic effort to not only develop a safe and effective vaccine in record time, but also distribute it on a global scale.

As one of the largest healthcare companies in the world, J&J has systems in place, including a partnership between the Biomedical Advanced Research and Development Authority (BARDA), which could potentially bolster the rollout of its vaccine.

As part of Operation War Speed, Johnson & Johnson is scheduled to deliver an initial batch of 100 million doses of its vaccine to the United States federal government.

"As a one-dose vaccine, people do not have to return for a second dose to be protected. In addition, this vaccine does not need to be kept in a freezer and can be stored at refrigerated temperatures — so it is easy to transport and store and allows for expanded availability in most community settings and mobile sites, as supply scales up," Walensky pointed out. "This third safe, effective COVID-19 vaccine comes at a potentially pivotal time. CDC’s latest data suggest that recent declines in COVID-19 cases may be stalling and potentially leveling off at still very high numbers."

J&J says it aims to ramp up production and deliver one billion doses of its vaccine in 2021. Since it’s a single-dose vaccine, it could help protect up to one billion people.

Medically reviewed in February 2021.

Centers for Disease Control and Prevention. Pfizer-BioNTech COVID-19 Vaccine: Storage and Handling Summary. Feb 16, 2021.
U.S. Food and Drug Administration. “FDA Briefing Document Janssen Ad26.COV2.S Vaccine for the Prevention of COVID-19.” Feb 26, 2021.
Johnson & Johnson. "Johnson & Johnson Announces Submission of Application to the U.S. FDA for Emergency Use Authorization of its Investigational Single-Shot Janssen COVID-19 Vaccine Candidate." Feb 4, 2021.
Johnson & Johnson. “Johnson & Johnson Announces Single-Shot Janssen COVID-19 Vaccine Candidate Met Primary Endpoints in Interim Analysis of its Phase 3 ENSEMBLE Trial.” Jan 29, 2021.
U.S. National Institutes of Health. “Janssen Investigational COVID-19 Vaccine: Interim Analysis of Phase 3 Clinical Data Released.” Jan 29, 2021.
C-Span. “White House COVID-19 Response Team News Conference.” Jan 29, 2021.
van Riel, D., de Wit, E. Next-generation vaccine platforms for COVID-19. Nat. Mater. 19, 810–812 (2020).
Centers for Disease Control and Prevention. “Understanding and Explaining Viral Vector COVID-19 Vaccines.” Jan 5, 2021.
Johnson & Johnson. “COVID-19 Update: Your Latest Questions About Johnson & Johnson's Investigational Vaccine Candidate Answered.” Jan 5, 2021.
Johnson& Johnson. “Johnson & Johnson Announces a Lead Vaccine Candidate for COVID-19; Landmark New Partnership with U.S. Department of Health & Human Services; and Commitment to Supply One Billion Vaccines Worldwide for Emergency Pandemic Use.” Mar 30, 2020.
U.S. Department of Health and Human Services. “HHS, DOD Collaborate With Johnson & Johnson to Produce Millions of COVID-19 Investigational Vaccine Doses.” Aug 5, 2020.

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