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What are the storage requirements for your vaccine?

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What are the storage requirements for your vaccine?

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What is the minimum purchase order for your vaccine?

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What is the minimum purchase order for your vaccine?

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What are some side effects associated with your vaccine?

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What are some side effects associated with your vaccine?

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Can your vaccine be modified to target COVID variants?

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Can your vaccine be modified to target COVID variants?

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What is an efficacy rate and what is the efficacy rate for your vaccine?

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What is an efficacy rate and what is the efficacy rate for your vaccine?

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What were the demographics for Johnson & Johnson clinical trial and how many participants?

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What were the demographics for Johnson & Johnson clinical trial and how many participants?

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What is the current status of the vaccine? The dosage amount & timeline. 

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What is the current status of the vaccine? The dosage amount & timeline. 

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How was your vaccine made and how does it works?

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How was your vaccine made and how does it works?

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Innovation Employee Spotlight

With its Phase 3 clinical trial now fully enrolled, the Global Head of Research & Development at Janssen brings us up to speed on the progress of the company's vaccine candidate, including upcoming key milestones.

By Hallie Levine

A

s the COVID-19 pandemic continues to impact people around the world, so does the quest to develop vaccines that are safe and effective in protecting individuals against the novel coronavirus.

Johnson & Johnson is one of many companies hard at work on an investigational COVID-19 vaccine candidate-work that included recruiting adults of all ages and ethnicities for a Phase 3 clinical trial known as ENSEMBLE, which is now fully enrolled with approximately45,000 participants.

Mathai Mammen, M.D., Ph.D., Global Head, Janssen Research & Development, Johnson & Johnson, has been helping to spearhead these efforts since lastJanuary. His goal: ensure a safe, effective and easily distributed and administered vaccine is accessible at scalefor people around the globe.

With company scientists anticipating efficacy and safety data for this trial for review by the end of this month, we sat down with Dr. Mammen for an update on his team's latest research and development milestones as they work toward a once-in-a-century public health achievement.

Q:

It can take years to develop a vaccine. How were scientists at Janssen able to mobilize so quickly?

A:

The unprecedented speed of our vaccine development was dependent upon several things: collaborations and partnerships with government, regulatory authorities and the scientific community around the world, both in terms of funding and pooling knowledge;our ability to streamline the production process based on past experience with vaccine development; and our ability to invest at scale well ahead of clinical studies. Unfortunately, the fact that the virus has been circulating so abundantly in the world also made it possible to test the vaccine candidate against COVID-19 substantially faster.

LastJanuary, we obtained the novel coronavirus' sequence information from China-that is, information about its genome, or genetic material-and validated it.

Due to our extensive previous experience with vaccine technology-we used the same technology to create ourEuropean Commission-approved Ebola vaccine-scientists already had a good sense of the best doses to use for the investigational COVID-19 candidate.

From there, we collaborated closely with Dan Barouch, M.D., Ph.D., and his team at the Center for Virology and Vaccine Research at theBeth Israel Deaconess Medical Center, an affiliate of Harvard Medical School, to design a large number of potential candidates for the vaccine. We had previously collaborated with Dr. Barouch on preclinical work for our Zika and HIV vaccine candidates.

We also partnered with the Biomedical Advanced Research and Development Authority (BARDA), a component of the Office of the Assistant Secretary for Preparedness and Response in the U.S. Department of Health and Human Services, to commit equally tomore than $1 billion to cofund research, development and clinical testing for a potential COVID-19 vaccine.

From March to June, we experimented with various candidates, whittling the field down to two in June-and finally getting it down to one in July.

We then combined the traditional first two research phases of a clinical trial into one phase, known as Phase 1/2a, so we could examine our candidate's safety and immune response within a couple of months. A traditional approach may have taken up to a year.

This was possible, in part, because our discovery and manufacturing teams were able to execute several steps in parallel that they normally would have executed sequentially. And due to our extensive previous experience with vaccine technology-we used the same technology to create ourEuropean Commission-approved Ebola vaccine -scientists already had a good sense of the best doses to use for the investigational COVID-19 vaccine candidate.

Once we had strong interim data from the Phase 1/2a trial, we were able to move into Phase 3 clinical trials with a chosen dose. During Phase 3, many more people receive the vaccine to thoroughly test safety and efficacy. And the more people who can be vaccinated at this point, the sooner researchers can gather conclusive results.

Q:

How is your Phase 3 single-dose ENSEMBLE trial going?

A:

It's proceeding very well. We began recruiting participants for it at the end of September, once we got the Phase 1/2a data in.

We used extensive disease modeling and simulation from our data science team, in partnership with MIT, to predict where COVID-19 incidence at a regional level would be highest, and where the populations we wished to focus on were based. We picked our trial sites based on this Janssen-MIT machine learning model, and have benefited significantly in speed from these choices.

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The trial is now fully enrolled with roughly 45,000 adult participants. In fact, ENSEMBLE is the fastest enrolled trial in Johnson & Johnson history-we secured these participants in less than four months.

A lot of effort was also put toward ensuring all races, ethnicities, ages and medical backgrounds are represented in our clinical trials. While diversity is important in all of our research at Janssen, it's especially crucial for the investigational COVID-19 vaccine, because the virus disproportionately affects Black and Latinx communities, for example. So we have been committed to ensuring that these populations are well represented in our clinical trials.

Our site selection model was very important in placing us in areas of high diversity for this clinical trial. We then employed a large number of methods to ensure that we pulled through diverse participants.

Our ENSEMBLE study protocol includes both 14-day and 28-day endpoints. ( Endpoints are the primary outcomes being measured in a clinical trial, like physical symptoms or test results showing protection against disease.) Our expectation is that full immunity is reached after day 28, and that we may see some protection as early as 14 days.

As of today, all participants have been randomized to receive either one dose of the vaccine or a placebo. The next step in the process is to review the efficacy and safety data from that trial, which we anticipate receiving by the end of this month. As an "event-based study," meaning that we need a certain number of randomly occurring events to occur prior to analysis, the exact timing of when we will see data is somewhat uncertain.

Q:

You are also studying a two-dose regimen. Can you tell us more about this?

A:

At Johnson & Johnson, we're extremely thorough and driven by science. The ENSEMBLE 2 study, which we're now recruiting for, will give participants two doses of the vaccine spaced two months apart. The reason we are running this second study is to see if a second dose might provide greater, or longer, protection.

Q:

What percentage efficacy are you looking for?

A:

COVID-19 vaccine manufacturers are reporting efficacy rates greater than 90%, and we too would like high efficacy.

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We do have long-term safety data for our vaccine platform; more that 140,000 people have received vaccines and vaccine candidates using the platform.

And we feel very confident in our one-dose regimen. Since we spent so much time and effort in zeroing in on one specific antigen, we were able to optimize it and make it as strong as possible.

Q:

Can you tell us more about how your investigational vaccine works?

A:

Unlike mRNA vaccines, which use messengerRNA to create a protein that prompts an immune response in the body, our investigational COVID-19 vaccine uses an adenovirus-a type of virus that causes the common cold-that has been made unable to replicate. The adenovirus carries a gene from the coronavirus into human cells, which then produce thecoronavirusspike protein, but not the coronavirus itself. This spike protein is what primes the immune system to fight off a subsequent infection by the virus.

There are a couple advantages to this approach. First, the adenovirus is well known in the human population. And we've used it before, in our Ebola vaccine and in investigational vaccines for HIV and RSV, so we have a lot of long-term safety data for it.

Secondly, it helps make a vaccine temperature stable.

The vaccine technology we've used can remain stable for two years at -4° F, and at least three months at 35-46° F, which is about the temperature of your home refrigerator. It may be stable for even longer at refrigerator temperatures, and we are actively collecting stability data now to see how long we can go.We believe this stability will help make it easier to transport and distribute our COVID-19 vaccine candidatewithout the need for shipping at special temperatures.

Q:

What are the next key milestones for your vaccine candidate?

A:

Once we receive efficacy and safety data from our Phase 3 study, which should come in later this month, we'll be looking for very specific endpoints.

We're hoping these milestones can come together by February, so that we can then consider applying for an emergency use authorization of our vaccine with the FDA, as well as regulatory filings in other countries.

Our endpoint looks at whether our investigational vaccine prevents someone from getting sick with moderate to severe COVID-19-meaning they show at least two symptoms, such as a fever and cough-as well as if that person has a positive PCR test, which detects the virus' genetic material. We measure this at different timepoints to see when the protection will kick in.

The other big milestone is manufacturing. We need to ensure all aspects of our COVID-19 vaccine development program meet our safety and quality standards, and that all of our manufacturing and distribution processes comply with all applicable regulations. This includes our raw materials and other components; procedures; manufacturing facilities; testing laboratories, including equipment and analytical methods; shipping and routes; and shelf life and stability.

We're hoping these milestones can come together by February, so that we can then consider applying for an Emergency Use Authorization (EUA) of our vaccine with the U.S. Food and Drug Administration (FDA), as well as regulatory filings in other countries.

We've committed to not-for-profit pricing during the pandemic period if we are granted EUA (or its equivalent) in any region of the world.We want to bring an affordable vaccine to the public, with the goal of providing 1 billion doses in 2021 and more after that.

Q:

What do you personally think is most remarkable about the race to create a potential COVID-19 vaccine?

A:

The devotion of every single person involved in these clinical trials.

There are so many employees who are pouring immense creativity into this program and working nonstop as part of the effort to deliver a vaccine at record speed. I also have immense gratitude for our study investigators and coordinators, nurses and other frontline healthcare workers.

I have also been very pleased with the collaboration across our industry. I led a vaccine group under the COVID R&D Alliance in which different organizations helped one another in all sorts of ways, and ensured that the industry was going to deliver a definitive solution to this pandemic. I have never seen such collaborative behavior across companies in my career.

On a final note, I have so much admiration and respect for all the people who have signed up to be in our clinical trials. They wanted to help wage the war against COVID-19 and make our world a safer, better place. They are heroes.

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COVID-19 Update: Your Latest Questions About Johnson & Johnson's Investigational Vaccine Candidate Answered

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Innovation Employee Spotlight With its Phase 3 clinical trial now fully enrolled, the Global Head of Research & Development at Janssen brings us up to speed on the progress of the company's vaccine candidate, including upcoming key milestones.

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n an ideal world, a pandemic vaccine could be delivered in a single shot, so supplies could be stretched to cover a lot of people. It would trigger no side effect more significant than a sore arm. And it would be easy to ship and store.

We now have one such vaccine.

On Feb. 27, the Food and Drug Administration announced it had issued an emergency use authorization for Johnson & Johnson's one-dose Covid vaccine. Developed by J&J's vaccines division, Janssen Pharmaceuticals, it was shown to be 66% protective against moderate to severe Covid infection in a multi-country study. Importantly, it was 85% effective in protecting against severe disease. And there were no hospitalizations or deaths among people in the vaccine arm of a large clinical trial.

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Overall efficacy varied a bit geographically, especially in South Africa, where a new variant appears to evade to some degree the immunity induced both by infection and by Covid vaccines, which were designed to target earlier strains of the SARS-CoV-2 virus.

Rollout of the vaccine has already started, though the company is not expected to be able to supply substantial numbers of doses until April.

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Earlier STAT published a head-to-head comparison of the vaccines developed by Pfizer and its partner, BioNTech, and by Moderna, which have been in use in the country since December. We have updated it here with information about the J&J vaccine.

Please note that in the initial rollout of vaccine, individuals are unlikely to be offered a choice of which vaccine they want. Supplies are too scarce. The vaccine available at the place where you are being vaccinated is the one you'll get.

Vaccine types

The Pfizer and Moderna vaccines are made using messenger RNA, or mRNA, a technology that delivers a bit of genetic code to cells - in effect, a recipe to make the surface protein (known as spike) on the SARS-2 virus. The proteins made with the mRNA instructions activate the immune system, teaching it to see the spike protein as foreign and develop antibodies and other immunity weapons with which to fight it.

The J&J vaccine uses a different approach to instruct human cells to make the SARS-2 spike protein, which then triggers an immune response. It is what's known as a viral vectored vaccine. A harmless adenovirus - from a large family of viruses, some of which cause common colds - has been engineered to carry the genetic code for the SARS-2 spike protein. Once the adenovirus enters cells, they use that code to make spike proteins. J&J employed this same approach to make an Ebola vaccine that has been authorized for use by the European Medicines Agency.

Target population

The Pfizer vaccine has been authorized for use for people aged 16 and older. Moderna's has been cleared for use in people 18 and older, though the company is now testing its vaccine in 12- to 17-year-olds. J&J's vaccine has been tested in people 18 and older, and that's who it was authorized for. Until testing in children and younger teens is conducted, this vaccine won't be available for use anyone under 18 years old either.

Vaccine efficacy

The Pfizer and Moderna vaccines have shown astonishing - and essentially equivalent - degrees of efficacy, at least in the early stages after vaccination.

The Pfizer vaccine showed efficacy of 95% at preventing symptomatic Covid infection after two doses. The vaccine appeared to be more or less equally protective across age groups and racial and ethnic groups.

The Moderna vaccine was 94.1% effective at preventing symptomatic Covid-19 after the second dose. The vaccine's efficacy appeared to be slightly lower in people 65 and older, but during a presentation to the Food and Drug Administration's advisory committee in December, the company explained that the numbers could have been influenced by the fact there were few cases in that age group in the trial. The vaccine appeared to be equally effective across different ethnic and racial groups.

But comparing the efficacy of those vaccines to the efficacy of Johnson & Johnson's is challenging because of differences in the designs of the Phase 3 clinical tests - essentially the trials were testing for different outcomes. Pfizer's and Moderna's trials both tested for any symptomatic Covid infection. Pfizer started counting cases from seven days after receipt of the second dose of vaccine, while Moderna waited until day 14 to start counting cases.

J&J, by contrast, sought to determine whether one dose of its vaccine protected against moderate to severe Covid illness - defined as a combination of a positive test and at least one symptom such as shortness of breath, beginning from 14 or 28 days after the single shot. (The company collected data for both.)

Because of the difference in the trials, making direct comparisons is a bit like comparing apples and oranges. Additionally, Pfizer and Moderna's vaccines were tested before the emergence of troubling new variants in Britain, South Africa, and Brazil. It's not entirely clear how well they will work against these mutated viruses.

The J&J vaccine was still being tested when the variants were making the rounds. Much of the data generated in the South African arm of the J&J trial involved people who were infected with the variant first seen in South Africa, called B.1.351.

The J&J one-dose vaccine was shown to be 66% protective against moderate to severe Covid infections overall from 28 days after injection, though there was variability based on geographic locations. The vaccine was 72% protective in the United States, 66% protective in South America, and 57% protective in South Africa.

But the vaccine was shown to be 85% protective against severe disease, with no differences across the eight countries or three regions in the study, nor across age groups among trial participants. And there were no hospitalizations or deaths in the vaccine arm of the trial after the 28-day period in which immunity developed.

It's not yet known if any of these vaccines prevent asymptomatic infection with the SARS-CoV-2 virus. Nor is it known if vaccinated people can transmit the virus if they do become infected but don't show symptoms.

Number of doses/amounts of vaccine per dose

Both the Moderna and the Pfizer vaccines require two shots: a priming dose, followed by a booster shot. The interval between Moderna doses is 28 days; for the Pfizer vaccine, it's 21 days.

Each dose of Pfizer's contains 30 micrograms of vaccine. Moderna went with a much larger dose of vaccine, 100 micrograms. It means the company is using a little more than three times as much vaccine per person as Pfizer is. And yet, they aren't getting better results. The government's vaccine development program, formerly called Operation Warp Speed, has asked Moderna to test if it could lower the dosage of its vaccine without eroding the vaccine's protection.

The J&J vaccine is, as mentioned, a single-dose vaccine. The company is also testing a two-dose regimen, with the two shots given eight weeks apart. The results from that 30,000-person trial aren't expected until sometime in May. The single dose contains more antigen than the individual doses in the two-dose regimen.

J&J is also testing what happens to antibody responses when a person who received the single dose regimen receives a small booster shot quite a bit later, Johan Van Hoof, managing director of Janssen Vaccines revealed recently. Van Hoof didn't say how long the interval is between the single shot and the small booster, nor did he say when J&J expects results from that study.

Side-effect profile

In the vernacular of vaccinology, shots that trigger a range of transient side effects in a lot of recipients are known as reactogenic.

All of these vaccines - in fact, most if not all the Covid-19 vaccines that have reported data so far - fall into the reactogenic category. The Advisory Committee on Immunization Practices, an expert panel that helps the Centers for Disease Control and Prevention set vaccination policies, advised hospitals early in the rollout that they might want to stagger vaccinations among employees in case some feel too unwell to work the day after being vaccinated.

The most common side effects are injection site pain, fatigue, headache, muscle pain, and joint pain. Some people in the clinical trials have reported fever. With the Pfizer and Moderna vaccines, side effects are more common after the second dose. Younger adults, who have more robust immune systems, reported more side effects than older adults.

To be clear: These side effects are a sign of an immune system kicking into gear. They do not signal that the vaccine is unsafe. To date there are no serious, long-term side effects associated with receipt of these vaccines, which will be closely monitored as their use expands.

There have been reports of severe allergic reactions to the mRNA vaccines. Both the Pfizer and Moderna vaccines appear, on rare occasions, to trigger anaphylaxis, a severe and potentially life-threatening reaction. People who develop anaphylaxis must be treated with epinephrine - the drug in EpiPens - and may need to be hospitalized to ensure their airways remain open. The CDC says people should be monitored for 15 minutes after getting a Covid-19 shot, and 30 minutes if they have a history of severe allergies.

J&J recently revealed that a single case of anaphylaxis has been reported in someone who received its vaccine.

It will take time to come up with a firm estimate of how frequently this side effect occurs. The most recent data from the CDC suggest that anaphylaxis occurs at a rate of about 2.5 cases per one million doses given of the Moderna vaccine, and 4.7 cases per million doses of the Pfizer. Many of the people who have developed anaphylaxis have a history of severe allergies and some have had previous episodes of anaphylaxis.

Safety for those who are pregnant or lactating

None of the vaccines has been tested in these two groups, although Pfizer recently began a Phase 2/3 trial to test the safety and efficacy of its vaccine during pregnancy. Van Hoof said J&J will begin a similar trial in late March or early April.

Moderna has completed animal studies the FDA demanded of manufacturers; these studies look for evidence that the vaccine might harm the pregnancy or the developing fetus. The company said it saw no such signals.

The CDC recommends until those studies are conducted, the choice of whether to get vaccinated should rest with the person who is pregnant or lactating. This is a more permissive stance than has been taken in some countries, which have said people who are pregnant should not be vaccinated with these vaccines.

Storage requirements

The mRNA vaccines require an elaborate cold chain, the term used to describe the conditions under which vaccines must be stored during distribution and when they are in the doctors' offices, pharmacies, or public health clinics where they'll be administered.

The J&J shot does not, which means this vaccine can be given easily anywhere - in doctors' offices, pharmacies, mass vaccination sites, public health clinics - once supplies are adequate. It can be stored for at least three months at the temperature of a regular refrigerator.

Of the mRNA vaccines, Pfizer's was originally the more difficult to use. It had to be shipped and stored in ultra-cold freezers - ones that could keep the vials at -94 degrees Fahrenheit. But recently, the FDA announced that the vaccine can be shipped and stored - for a two-week period only - at temperatures of normal pharmacy freezers, between -13 and 5 degrees Fahrenheit. That should make the final stage of the vaccine's journey from production plant to syringe ready to plunge into an arm somewhat easier.

Moderna's must be shipped at -4 degrees Fahrenheit, which is within the temperature of a regular refrigerator freezer.

After thawing, a vial of the Pfizer vaccine must be used within five days; Moderna's is stable at fridge temperature for 30 days and at room temperature for 12 hours. J&J's vaccine can be stored at room temperature - not to exceed 77 degrees Fahrenheit - for 12 hours when the vial hasn't yet been punctured. After the first dose is withdrawn, the vial can be stored in a fridge for six hours or at room temperature for two hours.

Minimum purchase order

The cold-chain requirement is not the only challenging aspect of the Pfizer vaccine. The minimum amount of vaccine a location can order is 1,170 doses. A large teaching hospital might need several of those. But there are plenty of places across the country that would not have needed 1,000 doses to vaccinate the people eligible for vaccination in the early stages of the rollout, when only selected groups of people were eligible to get vaccine. As states move into vaccinating larger segments of the population, this large minimum order size become less of a disadvantage.

The Moderna vaccine's minimum order is 140 doses, a much more manageable number.

STAT has asked J&J several times what its minimum order will be; the company has not yet disclosed that information.

The Pfizer vaccine is shipped in six-dose vials. Moderna's vaccine comes in 14-dose vials. J&J's vaccine is packaged in five-dose vials.

Durability of protection

Figuring out how long the protection provided by any of these vaccines will last will take time. It's going to involve periodic blood draws from some volunteers to see what their antibody levels look like, though a decline in antibody levels doesn't necessarily equate to loss of protection.

But a large part of this work will involve watching for reports that people who were immunized are starting to contract Covid in larger numbers, a development that would probably lead to recommendations to give people booster shots at some yet-to-be-determined interval.
This story was last updated on Feb. 28. An earlier version of this story mischaracterized the way in which viral vectored vaccines work.

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Comparing three Covid-19 vaccines: Pfizer, Moderna, J&J

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n an ideal world, a pandemic vaccine could be delivered in a single shot, so supplies could be stretched to cover a lot of people. It would trigger no side effect more significant than a sore arm. And it would be easy to ship and store. We now have one such vaccine.

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Johnson & Johnson is testing a coronavirus vaccine known as JNJ-78436735 or Ad26.COV2.S. Clinical trials showed that a single dose of the vaccine had an efficacy rate of 72 percent in the United States, and a lower efficacy in countries where more contagious variants are widespread. The vaccine has been authorized for emergency use by the European Union, the United States and other countries.

Janssen Pharmaceutica, a Belgium-based division of Johnson & Johnson, developed the vaccine in collaboration with Beth Israel Deaconess Medical Center.

A Piece of the Coronavirus

The SARS-CoV-2 virus is studded with proteins that it uses to enter human cells. These so-called spike proteins make a tempting target for potential vaccines and treatments.

The Johnson & Johnson vaccine is based on the virus's genetic instructions for building the spike protein. But unlike the Pfizer-BioNTech and Moderna vaccines, which store the instructions in single-stranded RNA, the Johnson & Johnson vaccine uses double-stranded DNA.

DNA Inside an Adenovirus

The researchers added the gene for the coronavirus spike protein to another virus called Adenovirus 26. Adenoviruses are common viruses that typically cause colds or flu-like symptoms. The Johnson & Johnson team used a modified adenovirus that can enter cells but can't replicate inside them or cause illness.

Johnson & Johnson's vaccine comes out of decades of research on adenovirus-based vaccines. In July, the first one was approved for general use - a vaccine for Ebola, also made by Johnson & Johnson. The company is also running trials on adenovirus-based vaccines for other diseases, including H.I.V. and Zika. Some other coronavirus vaccines are also based on adenoviruses, such as the one developed by the University of Oxford and AstraZeneca using a chimpanzee adenovirus.

Adenovirus-based vaccines for Covid-19 are more rugged than mRNA vaccines from Pfizer and Moderna. DNA is not as fragile as RNA, and the adenovirus's tough protein coat helps protect the genetic material inside. As a result, the Johnson & Johnson vaccine can be refrigerated for up to three months at 36-46°F (2-8°C).

Entering a Cell

After the vaccine is injected into a person's arm, the adenoviruses bump into cells and latch onto proteins on their surface. The cell engulfs the virus in a bubble and pulls it inside. Once inside, the adenovirus escapes from the bubble and travels to the nucleus, the chamber where the cell's DNA is stored.

The adenovirus pushes its DNA into the nucleus. The adenovirus is engineered so it can't make copies of itself, but the gene for the coronavirus spike protein can be read by the cell and copied into a molecule called messenger RNA, or mRNA.

Building Spike Proteins

The mRNA leaves the nucleus, and the cell's molecules read its sequence and begin assembling spike proteins.

Some of the spike proteins produced by the cell form spikes that migrate to its surface and stick out their tips. The vaccinated cells also break up some of the proteins into fragments, which they present on their surface. These protruding spikes and spike protein fragments can then be recognized by the immune system.

The adenovirus also provokes the immune system by switching on the cell's alarm systems. The cell sends out warning signals to activate immune cells nearby. By raising this alarm, the Johnson & Johnson vaccine causes the immune system to react more strongly to the spike proteins.

Spotting the Intruder

When a vaccinated cell dies, the debris contains spike proteins and protein fragments that can then be taken up by a type of immune cell called an antigen-presenting cell.

The cell presents fragments of the spike protein on its surface. When other cells called helper T cells detect these fragments, the helper T cells can raise the alarm and help marshal other immune cells to fight the infection.

Making Antibodies

Other immune cells, called B cells, may bump into the coronavirus spikes on the surface of vaccinated cells, or free-floating spike protein fragments. A few of the B cells may be able to lock onto the spike proteins. If these B cells are then activated by helper T cells, they will start to proliferate and pour out antibodies that target the spike protein.

Stopping the Virus

The antibodies can latch onto coronavirus spikes, mark the virus for destruction and prevent infection by blocking the spikes from attaching to other cells.

Killing Infected Cells

The antigen-presenting cells can also activate another type of immune cell called a killer T cell to seek out and destroy any coronavirus-infected cells that display the spike protein fragments on their surfaces.

Remembering the Virus

Johnson & Johnson's vaccine is given as a single dose, unlike the two-dose coronavirus vaccines from Pfizer, Moderna and AstraZeneca.

Researchers don't yet know how long the vaccine's protection might last. It's possible that the number of antibodies and killer T cells will drop in the months after vaccination. But the immune system also contains special cells called memory B cells and memory T cells that might retain information about the coronavirus for years or even decades.

Vaccine Timeline

Johnson & Johnson begins work on a coronavirus vaccine.

A Phase 1/2 trial begins. Unlike the clinical trials for other leading vaccines, the trial involves one dose, not two.

Preliminary results from the Phase 3 trial are expected in January. The company is aiming to produce at least a billion doses this year.

The vaccine had a 72 percent overall efficacy rate in the United States and 64 percent in South Africa, where a highly contagious variant called B.1.351 emerged in the fall and is now driving most cases. The vaccine also showed efficacy against severe forms of Covid-19.

Sources: National Center for Biotechnology Information; Nature; Lynda Coughlan, University of Maryland School of Medicine.

Tracking the Coronavirus

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Johnson & Johnson is testing a coronavirus vaccine known as JNJ-78436735 or Ad26.COV2.S. Clinical trials showed that a single dose of the vaccine had an efficacy rate of 72 percent in the United States, and a lower efficacy in countries where more contagious variants are widespread.

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On Tuesday, Feb. 24, the U.S. Food and Drug Administration released the results of its trial of the Johnson & Johnson coronavirus vaccine. The FDA found the vaccine to be safe and effective and it is expected to grant emergency use authorization in the coming days. Maureen Ferran, a virologist at the Rochester Institute of Technology, explains how this new vaccine works and explores the differences between it and the already approved Moderna and Pfizer-BioNTech vaccines.
How does the Johnson & Johnson vaccine work?

The Johnson & Johnson vaccine is what's called a viral vector vaccine.

To create this vaccine, the Johnson & Johnson team took a harmless adenovirus - the viral vector - and replaced a small piece of its genetic instructions with coronavirus genes for the SARS-CoV-2 spike protein.

After this modified adenovirus is injected into someone's arm, it enters the person's cells. The cells then read the genetic instructions needed to make the spike protein and the vaccinated cells make and present the spike protein on their own surface. The person's immune system then notices these foreign proteins and makes antibodies against them that will protect the person if they are ever exposed to SARS-CoV-2 in the future.

The adenovirus vector vaccine is safe because the adenovirus can't replicate in human cells or cause disease, and the SARS-CoV-2 spike protein can't cause COVID-19 without the rest of the coronavirus.

This approach is not new. Johnson & Johnson used a similar method to make its Ebola vaccine, and the AstraZeneca-Oxford COVID-19 vaccine is also an adenovirus viral vector vaccine.

How effective is it?

The FDA's analysis found that, in the U.S., the Johnson & Johnson COVID-19 vaccine was 72% effective at preventing all COVID-19 and 86% effective at preventing severe cases of the disease. While there is still a chance a vaccinated person could get sick, this suggests they would be much less likely to need hospitalization or to die from COVID-19.

A similar trial in South Africa, where a new, more contagious variant is dominant, produced similar results. Researchers found the Johnson & Johnson vaccine to be slightly less effective at preventing all illness there - 64% overall - but was still 82% effective at preventing severe disease. The FDA report also indicates that the vaccine protects against other variants from Britain and Brazil too.

How is it different from the Moderna and Pfizer vaccines?

The most basic difference is that the Johnson & Johnson vaccine is an adenovirus vector vaccine, while the Moderna and Pfizer vaccines are both mRNA vaccines. Messenger RNA vaccines use genetic instructions from the coronavirus to tell a person's cells to make the spike protein, but these don't use another virus as a vector. There are many practical differences, too.

Both of the mRNA-based vaccines require two shots. The Johnson & Johnson vaccine requires only a single dose. This is key when vaccines are in short supply.

The Johnson & Johnson vaccine can also be stored at much warmer temperatures than the mRNA vaccines. The mRNA vaccines must be shipped and stored at below-freezing or subzero temperatures and require a complicated cold chain to safely distribute them. The Johnson & Johnson vaccine can be stored for at least three months in a regular refrigerator, making it much easier to use and distribute.

As for efficacy, it is difficult to directly compare the Johnson & Johnson vaccine with the mRNA vaccines due to differences in how the clinical trials were designed. While the Moderna and Pfizer vaccines are reported to be approximately 95% effective at preventing illness from COVID-19, the trials were done over the summer and fall of 2020, before newer more contagious variants were circulating widely. The Moderna and Pfizer vaccines might not be as effective against the new variants, and Johnson & Johnson trials were done more recently and take into account the vaccine's efficacy against these new variants.

Should I choose one type of vaccine over another?

Although the overall efficacy of the Moderna and Pfizer vaccines is higher than the Johnson & Johnson vaccine, you should not wait until you have your choice of vaccine - which is likely a long way off anyway. The Johnson & Johnson vaccine is nearly as good as the mRNA-based vaccines at preventing serious disease, and that's what really matters.

The Johnson & Johnson vaccine and other viral-vector vaccines like the one from AstraZeneca are particularly important for the global vaccination effort. From a public health perspective, it's important to have multiple COVID-19 vaccines, and the Johnson & Johnson vaccine is a very welcome addition to the vaccine arsenal. It doesn't require a freezer, making it much easier to ship and store. It's a one-shot vaccine, making logistics much easier compared with organizing two doses per person.

As many people as possible need to be vaccinated as quickly as possible to limit the development of new coronavirus variants. Johnson & Johnson is expected to ship out nearly four million doses as soon as the FDA grants emergency use authorization. Having a third authorized vaccine in the U.S. will be a big step towards meeting vaccination demand and stopping this pandemic.
Editor's note: This article is republished from The Conversation under a Creative Commons license. Read the original article. Johnson & Johnson is a funder of the PBS NewsHour.

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How does the Johnson & Johnson vaccine compare to other coronavirus vaccines?

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On Tuesday, Feb. 24, the U.S. Food and Drug Administration released the results of its trial of the Johnson & Johnson coronavirus vaccine. The FDA found the vaccine to be safe and effective and it is expected to grant emergency use authorization in the coming days.