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Understanding the One-Shot Johnson & Johnson COVID-19 Vaccine

Since the first COVID-19 vaccines became available, healthcare professionals, community workers, and politicians alike have been urging anyone eligible for a vaccine to get one. With cases still circulating in the U.S. and new variants threatening to worsen conditions, mass vaccination appears to be the best way out of the pandemic. 

There are currently three COVID-19 vaccines Moderna, Pfizer, and Johnson & Johnson (J&J), approved through Emergency Use Authorization (EUA) in the United States. The most recently approved vaccine, the Johnson & Johnson (Janssen) vaccine, was approved on February 27th, 2021, for all adults (18+). Over 1.5 million total vaccines have been administered in the country as of April 2, 2021. 

So, how does the J&J vaccine work, and how is it different (and similar) to the other vaccines available? In this post, we break down how the J&J vaccine works in the body and answer some common questions about the vaccine. 

How was the J&J vaccine researched?

The J&J vaccine had to complete the same research protocol and steps that are required for all routine vaccines before it applied for EUA from the Food and Drug Administration (FDA). There were 43,783 participants in the randomized, double-blind, placebo-controlled phase 3 clinical trial for the J&J vaccine. This means that participants were randomly sorted into two groups: the group that received the vaccine and a second group that received a saline (saltwater) injection instead. The research study was double-blind so neither the researchers nor the participants knew who was in which group; this helped prevent bias in the study results. After vaccination, both the placebo group and the vaccination group were followed to measure symptomatic cases of COVID-19. 

Who was included in the J&J vaccine trials?

The J&J research team strived to include a diverse population in terms of sex, age, and racial and ethnic identity in their study. The vaccine was tested across three continents and in 8 countries including the United States (44% of participants). Both males and females were included in the vaccine trials (54.9% male, 45.0% female). The vaccine was tested and proven to be effective in many different age groups: 66.5% of participants were 18-59 years old and 33.5% of participants were 60+ years old or older. And 41% of participants had chronic conditions that put them at higher risk for severe COVID-19.

In the U.S., the J&J trials included a racially and ethnically diverse group of participants that reflected the country’s population. Among these participants, 74% were White, 15% were Hispanic and/ or Latinx, 13% were Black/African American, 6% were Asian, and 1% were Native American.

How does the J&J vaccine work?

When an unvaccinated person is infected with COVID-19, the immune system recognizes the virus as a foreign invader and works to get rid of it by creating antibodies, which can recognize and destroy the virus. The immune system is then able to remember the virus and attack it if it ever encounters it again in the future. Vaccines work the same way, but provide immune protection without someone getting sick with the real virus first. Most antibodies made by the immune system for the COVID-19 virus recognize the spike (S) protein on the outside of the COVID-19 virus. This fact led scientists to ask: what if we can introduce the body to the S protein without actually exposing the body to the virus?

Image 1: How COVID-19 vaccines work in the body

This is precisely what all three vaccines do – deliver instructions into the body to prompt it to create the S protein.

While the J&J vaccine works similarly to the Pfizer and Moderna vaccines, it uses a slightly different mechanism for delivering the S protein instructions; whereas the Pfizer and Modern vaccines use mRNA, the J&J vaccine uses a viral vector. The vaccine uses an inactivated adenovirus vector to deliver the instructions for building the S protein into the body (See Image 1, step 1). The adenovirus vector is similar to the virus that causes the common cold, but it is modified, meaning it can’t replicate in the body or cause illness.

When the adenovirus vector is delivered to the body as a vaccine (step 2), it inserts its genetic material into the cell (step 3). The genetic material is transcribed into mRNA (step 4), which prompts the body to create S proteins. S proteins are then displayed on the outside of our body’s cells (step 5), and the immune system starts to recognize and build antibodies to target and destroy them.

The result? When a vaccinated person encounters the COVID-19 virus, it can quickly make antibodies to target the S protein from memory and destroy the virus before the person gets sick.

How does the J&J Vaccine Compare to the Pfizer or Moderna vaccines?

In clinical trials, all three vaccines showed nearly 100% efficacy at preventing death and hospitalizations due to COVID-19. All three vaccines demonstrated very high efficacy at preventing severe and symptomatic COVID-19 infections. Because each vaccine was tested on different populations at different times during the pandemic, it is difficult to compare the vaccine’s efficacy rates directly. For instance, Pfizer and Moderna’s vaccines were both tested when new COVID-19 variants weren’t yet circulating whereas J&J’s vaccine was tested when they were. The Pfizer and Moderna vaccines require two doses, three and four weeks apart, respectively, and the J&J vaccine currently only requires one dose.

Which vaccine should I get?

The J&J, Moderna, and Pfizer vaccines have all been proven to be highly safe and effective at preventing severe and symptomatic COVID-19. All three COVID-19 vaccines will greatly reduce the chances of being hospitalized or dying from COVID-19, which is the primary goal of any vaccine. Additionally, all three COVID-19 vaccines will help you protect your family and community by (likely) reducing the chances that you could spread the virus to others. In short, the best vaccine for you is the one you can get! By getting a COVID-19 vaccine – any one – we can all do our part to end the pandemic. 

What side effects can I expect after getting vaccinated with the J&J vaccine?

You may experience side effects after getting the J&J vaccines; however, these side effects are your body’s natural immune response and mean that your body is working hard to build immunity to the virus. According to the CDC, the most common side effects of the J&J vaccines include pain, redness, and swelling in the arm around the vaccination site, in addition to fatigue, headache, muscle pain, chills, fever, and nausea. These side effects usually appear within one to two days after the injection and typically resolve within a week. It is also completely normal to feel no side effects at all (and this doesn’t mean the vaccine isn’t working).

Does the J&J vaccine contain aborted fetal cells?

No, the J&J vaccine does not contain aborted fetal cells. Like many routine vaccinations (including MMR and hepatitis A), the J&J COVID-19 vaccine was developed by growing an inactivated adenovirus in a cell line developed from fetal cells. While the adenovirus grows in the cells, it is altered so that it can no longer replicate and cause disease in the human body, making the adenovirus a safe capsule through which to transport the COVID-19 vaccine into the body. Once the adenovirus is grown in the cells, the virus is purified, and any traces of the cells are removed. So the vaccine itself does not contain any fetal cells.

The fetal cells used in the development of the J&J vaccine were developed from one terminated pregnancy in 1985. Since 1985, the fetal cells have been allowed to replicate in the lab and no additional fetal tissue has been taken. The Vatican has released multiple statements urging Catholics to take the first COVID-19 vaccine made available to them, claiming it to be a moral imperative to save lives and prevent the further spread of COVID-19. 

When will the J&J vaccine (or any COVID-19 vaccine) be approved for children?

Currently, the Pfizer vaccine is the only COVID-19 vaccine approved for emergency use in children 16 years of age and older. Both the J&J vaccine and the Moderna vaccines are currently approved for adults 18 years and older. 

All COVID-19 vaccines are currently undergoing further study to test the safety and effectiveness of these vaccines in children. Johnson & Johnson is currently testing its vaccine in children between the ages of 12-18 years old. After this study concludes, the company plans on studying the vaccines in all children from birth to age 18. A COVID-19 vaccine will likely be made available to young children by 2022, but adolescent-aged children could be allowed to get a vaccine in late 2021.

The takeaway?

COVID-19 vaccines are our best tool for ending the pandemic. To get back to life, we will need enough of the population to be immune to the virus to prevent its spread and prevent the emergence of more variants. To reach this goal, we recommend getting vaccinated with the first vaccine that is available to you. Ending this pandemic will take all of us! 

Visit The Colorado Department of Public Health and Environment’s website for information on where and when you can get a COVID-19 vaccine in Colorado. For general questions about COVID-19 vaccines, visit the Center for Disease Control COVID-19 Resource Hub.  

Additionally, Immunize Colorado has developed a new fact sheet, COVID-19 Vaccines Approved for Emergency Use In the United States, that explains the differences between the Moderna, Pfizer, and J&J vaccines. The fact sheet can be easily accessed and shared online or downloaded and used as an informational flyer. 

If you have questions about COVID-19 vaccines, contact us at ICOffice@childrenscolorado.org

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